Reference / Curriculum / 3B / Chapter 14

3B · Chapter 14 · Solutions

Complete worked answer key

Answers and explanations for every original lesson practice set and chapter assessment.

Print this separately from student practice sheets. These are public worked solutions, not secure examination materials.

Units of Time

Prerequisite

60 — Six equal groups of ten contain 60 objects. You can represent this with six bundles of ten or six rows of ten counters.
65 — Add two tens to 45 while keeping the five ones unchanged: 45 + 10 = 55 and 55 + 10 = 65.
14 — One week contains seven days, so two complete weeks contain 7 + 7 = 14 days. The units change from weeks to days.

Understanding checks

125 min — Each hour is 60 minutes. 2 × 60 + 5 = 125 minutes.
185 s — Each minute contains 60 seconds. 3 × 60 + 5 = 185 seconds.
1 weeks 3 days — One week is seven days. 10 = 7 × 1 + 3.

Guided

215 s — Each minute contains 60 seconds. 3 × 60 + 35 = 215 seconds.
4 h 5 min — There are 4 full groups of 60 minutes and 5 more minutes.
4 min 10 s — Group the 250 seconds into complete 60-second minutes, then count the 10 remaining seconds.
215 min — Each hour is 60 minutes. 3 × 60 + 35 = 215 minutes.
195 s — Each minute contains 60 seconds. 3 × 60 + 15 = 195 seconds.

Independent

65 min — Each hour is 60 minutes. 1 × 60 + 5 = 65 minutes.
205 s — Each minute contains 60 seconds. 3 × 60 + 25 = 205 seconds.
1 h 45 min — There are 1 full groups of 60 minutes and 45 more minutes.
3 min 25 s — Group the 205 seconds into complete 60-second minutes, then count the 25 remaining seconds.
285 min — Each hour is 60 minutes. 4 × 60 + 45 = 285 minutes.
4 weeks 4 days — One week is seven days. 32 = 7 × 4 + 4.
1 h 15 min — There are 1 full groups of 60 minutes and 15 more minutes.
1 min 10 s — Group the 70 seconds into complete 60-second minutes, then count the 10 remaining seconds.

Challenge

315 minutes — Each hour has 60 minutes, so 5 hours 15 minutes is 300+15=315 minutes.
6 h 10 min — Trade 60 minutes for an extra hour, leaving 10 minutes.

Exit

255 min — Each hour is 60 minutes. 4 × 60 + 15 = 255 minutes.
95 s — Each minute contains 60 seconds. 1 × 60 + 35 = 95 seconds.
2 h 45 min — There are 2 full groups of 60 minutes and 45 more minutes.

Calculating Time — Part 1

Prerequisite

2 min 15 s — Group the 135 seconds into complete 60-second minutes, then count the 15 remaining seconds.
145 min — Each hour is 60 minutes. 2 × 60 + 25 = 145 minutes.
130 s — Each minute contains 60 seconds. 2 × 60 + 10 = 130 seconds.

Understanding checks

110 min — Count from 9:15 a.m. to the next whole hour, then onward to 11:05 a.m.. The intervals add to 110 minutes.
135 min — Count from 3:55 p.m. to the next whole hour, then onward to 6:10 p.m.. The intervals add to 135 minutes.
75 min — Count from 4:20 p.m. to the next whole hour, then onward to 5:35 p.m.. The intervals add to 75 minutes.

Guided

25 min — Count from 11:35 a.m. to the next whole hour, then onward to 12:00 p.m.. The intervals add to 25 minutes.
50 min — Count from 12:00 p.m. to the next whole hour, then onward to 12:50 p.m.. The intervals add to 50 minutes.
65 min — Count from 9:45 a.m. to the next whole hour, then onward to 10:50 a.m.. The intervals add to 65 minutes.
65 min — Count from 3:50 p.m. to the next whole hour, then onward to 4:55 p.m.. The intervals add to 65 minutes.
35 min — Count from 7:30 a.m. to the next whole hour, then onward to 8:05 a.m.. The intervals add to 35 minutes.

Independent

135 min — Count from 10:10 a.m. to the next whole hour, then onward to 12:25 p.m.. The intervals add to 135 minutes.
25 min — Count from 7:10 a.m. to the next whole hour, then onward to 7:35 a.m.. The intervals add to 25 minutes.
50 min — Count from 9:25 a.m. to the next whole hour, then onward to 10:15 a.m.. The intervals add to 50 minutes.
50 min — Count from 4:40 p.m. to the next whole hour, then onward to 5:30 p.m.. The intervals add to 50 minutes.
90 min — Count from 1:25 p.m. to the next whole hour, then onward to 2:55 p.m.. The intervals add to 90 minutes.
135 min — Count from 10:50 a.m. to the next whole hour, then onward to 1:05 p.m.. The intervals add to 135 minutes.
110 min — Count from 10:05 a.m. to the next whole hour, then onward to 11:55 a.m.. The intervals add to 110 minutes.
65 min — Count from 7:10 a.m. to the next whole hour, then onward to 8:15 a.m.. The intervals add to 65 minutes.

Challenge

12:20 p.m. — 15 minutes reach noon; then 20 more minutes reach 12:20 p.m.
Next day at 12:20 a.m. — 20 minutes reach midnight; 20 minutes more reach 12:20 a.m. on the next day.

Exit

135 min — Count from 10:55 a.m. to the next whole hour, then onward to 1:10 p.m.. The intervals add to 135 minutes.
35 min — Count from 4:30 p.m. to the next whole hour, then onward to 5:05 p.m.. The intervals add to 35 minutes.
75 min — Count from 12:35 p.m. to the next whole hour, then onward to 1:50 p.m.. The intervals add to 75 minutes.

Calculating Time — Part 2

Prerequisite

50 min — Count from 10:00 a.m. to the next whole hour, then onward to 10:50 a.m.. The intervals add to 50 minutes.
65 min — Count from 12:45 p.m. to the next whole hour, then onward to 1:50 p.m.. The intervals add to 65 minutes.
75 min — Count from 12:40 p.m. to the next whole hour, then onward to 1:55 p.m.. The intervals add to 75 minutes.

Understanding checks

2:30 p.m. — Add 110 minutes to the start time, crossing each next hour carefully. 12:40 p.m. plus 110 minutes is 2:30 p.m..
8:35 a.m. — Add 135 minutes to the start time, crossing each next hour carefully. 6:20 a.m. plus 135 minutes is 8:35 a.m..
3:40 p.m. — Add 35 minutes to the start time, crossing each next hour carefully. 3:05 p.m. plus 35 minutes is 3:40 p.m..

Guided

2:35 p.m. — Add 50 minutes to the start time, crossing each next hour carefully. 1:45 p.m. plus 50 minutes is 2:35 p.m..
12:30 p.m. — Add 50 minutes to the start time, crossing each next hour carefully. 11:40 a.m. plus 50 minutes is 12:30 p.m..
1:50 p.m. — Add 110 minutes to the start time, crossing each next hour carefully. 12:00 p.m. plus 110 minutes is 1:50 p.m..
11:50 a.m. — Add 90 minutes to the start time, crossing each next hour carefully. 10:20 a.m. plus 90 minutes is 11:50 a.m..
12:25 p.m. — Add 135 minutes to the start time, crossing each next hour carefully. 10:10 a.m. plus 135 minutes is 12:25 p.m..

Independent

12:45 p.m. — Add 75 minutes to the start time, crossing each next hour carefully. 11:30 a.m. plus 75 minutes is 12:45 p.m..
6:50 a.m. — Add 35 minutes to the start time, crossing each next hour carefully. 6:15 a.m. plus 35 minutes is 6:50 a.m..
3:55 p.m. — Add 75 minutes to the start time, crossing each next hour carefully. 2:40 p.m. plus 75 minutes is 3:55 p.m..
4:40 p.m. — Add 35 minutes to the start time, crossing each next hour carefully. 4:05 p.m. plus 35 minutes is 4:40 p.m..
8:40 a.m. — Add 65 minutes to the start time, crossing each next hour carefully. 7:35 a.m. plus 65 minutes is 8:40 a.m..
12:40 p.m. — Add 110 minutes to the start time, crossing each next hour carefully. 10:50 a.m. plus 110 minutes is 12:40 p.m..
1:20 p.m. — Add 35 minutes to the start time, crossing each next hour carefully. 12:45 p.m. plus 35 minutes is 1:20 p.m..
1:05 p.m. — Add 65 minutes to the start time, crossing each next hour carefully. 12:00 p.m. plus 65 minutes is 1:05 p.m..

Challenge

12:30 p.m. — 10 minutes reach noon; then 30 more minutes reach 12:30 p.m.
Next day at 12:30 a.m. — 15 minutes reach midnight; 30 minutes more reach 12:30 a.m. on the next day.

Exit

1:50 p.m. — Add 135 minutes to the start time, crossing each next hour carefully. 11:35 a.m. plus 135 minutes is 1:50 p.m..
3:35 p.m. — Add 110 minutes to the start time, crossing each next hour carefully. 1:45 p.m. plus 110 minutes is 3:35 p.m..
3:45 p.m. — Add 75 minutes to the start time, crossing each next hour carefully. 2:30 p.m. plus 75 minutes is 3:45 p.m..

Calculating Time — Part 3

Prerequisite

12:25 p.m. — Add 35 minutes to the start time, crossing each next hour carefully. 11:50 a.m. plus 35 minutes is 12:25 p.m..
10:55 a.m. — Add 90 minutes to the start time, crossing each next hour carefully. 9:25 a.m. plus 90 minutes is 10:55 a.m..
8:20 a.m. — Add 50 minutes to the start time, crossing each next hour carefully. 7:30 a.m. plus 50 minutes is 8:20 a.m..

Understanding checks

135 min — Count from 11:35 a.m. to the next whole hour, then onward to 1:50 p.m.. The intervals add to 135 minutes.
90 min — Count from 11:15 p.m. to the next whole hour, then onward to 12:45 a.m.. The intervals add to 90 minutes.
75 min — Count from 11:35 a.m. to the next whole hour, then onward to 12:50 p.m.. The intervals add to 75 minutes.

Guided

110 min — Count from 11:35 a.m. to the next whole hour, then onward to 1:25 p.m.. The intervals add to 110 minutes.
35 min — Count from 11:15 p.m. to the next whole hour, then onward to 11:50 p.m.. The intervals add to 35 minutes.
110 min — Count from 11:40 p.m. to the next whole hour, then onward to 1:30 a.m.. The intervals add to 110 minutes.
110 min — Count from 10:50 a.m. to the next whole hour, then onward to 12:40 p.m.. The intervals add to 110 minutes.
90 min — Count from 11:35 a.m. to the next whole hour, then onward to 1:05 p.m.. The intervals add to 90 minutes.

Independent

35 min — Count from 11:35 a.m. to the next whole hour, then onward to 12:10 p.m.. The intervals add to 35 minutes.
135 min — Count from 10:50 a.m. to the next whole hour, then onward to 1:05 p.m.. The intervals add to 135 minutes.
50 min — Count from 11:40 p.m. to the next whole hour, then onward to 12:30 a.m.. The intervals add to 50 minutes.
50 min — Count from 11:35 a.m. to the next whole hour, then onward to 12:25 p.m.. The intervals add to 50 minutes.
35 min — Count from 11:40 p.m. to the next whole hour, then onward to 12:15 a.m.. The intervals add to 35 minutes.
25 min — Count from 11:35 a.m. to the next whole hour, then onward to 12:00 p.m.. The intervals add to 25 minutes.
75 min — Count from 11:40 p.m. to the next whole hour, then onward to 12:55 a.m.. The intervals add to 75 minutes.
25 min — Count from 11:15 p.m. to the next whole hour, then onward to 11:40 p.m.. The intervals add to 25 minutes.

Challenge

12:40 p.m. — 5 minutes reach noon; then 40 more minutes reach 12:40 p.m.
Next day at 12:40 a.m. — 10 minutes reach midnight; 40 minutes more reach 12:40 a.m. on the next day.

Exit

135 min — Count from 11:40 p.m. to the next whole hour, then onward to 1:55 a.m.. The intervals add to 135 minutes.
110 min — Count from 11:15 p.m. to the next whole hour, then onward to 1:05 a.m.. The intervals add to 110 minutes.
50 min — Count from 11:15 p.m. to the next whole hour, then onward to 12:05 a.m.. The intervals add to 50 minutes.

Calculating Time — Part 4

Prerequisite

135 min — Count from 11:40 p.m. to the next whole hour, then onward to 1:55 a.m.. The intervals add to 135 minutes.
35 min — Count from 11:15 p.m. to the next whole hour, then onward to 11:50 p.m.. The intervals add to 35 minutes.
90 min — Count from 10:50 a.m. to the next whole hour, then onward to 12:20 p.m.. The intervals add to 90 minutes.

Understanding checks

12:20 p.m. — First reach 11:45 a.m. after walking, then add 35 minutes. Finish at 12:20 p.m..
7:00 a.m. — First reach 6:15 a.m. after walking, then add 45 minutes. Finish at 7:00 a.m..
11:55 a.m. — First reach 11:00 a.m. after walking, then add 55 minutes. Finish at 11:55 a.m..

Guided

2:45 p.m. — First reach 2:00 p.m. after walking, then add 45 minutes. Finish at 2:45 p.m..
9:35 a.m. — First reach 8:40 a.m. after walking, then add 55 minutes. Finish at 9:35 a.m..
9:15 a.m. — First reach 8:40 a.m. after walking, then add 35 minutes. Finish at 9:15 a.m..
3:50 p.m. — First reach 3:15 p.m. after walking, then add 35 minutes. Finish at 3:50 p.m..
6:20 p.m. — First reach 5:25 p.m. after walking, then add 55 minutes. Finish at 6:20 p.m..

Independent

2:45 p.m. — First reach 2:10 p.m. after walking, then add 35 minutes. Finish at 2:45 p.m..
11:20 a.m. — First reach 10:35 a.m. after walking, then add 45 minutes. Finish at 11:20 a.m..
2:40 p.m. — First reach 1:45 p.m. after walking, then add 55 minutes. Finish at 2:40 p.m..
3:00 p.m. — First reach 2:25 p.m. after walking, then add 35 minutes. Finish at 3:00 p.m..
2:10 p.m. — First reach 1:15 p.m. after walking, then add 55 minutes. Finish at 2:10 p.m..
1:00 p.m. — First reach 12:05 p.m. after walking, then add 55 minutes. Finish at 1:00 p.m..
5:30 p.m. — First reach 4:55 p.m. after walking, then add 35 minutes. Finish at 5:30 p.m..
11:10 a.m. — First reach 10:35 a.m. after walking, then add 35 minutes. Finish at 11:10 a.m..

Challenge

12:10 p.m. — 20 minutes reach noon; then 10 more minutes reach 12:10 p.m.
Next day at 12:10 a.m. — 25 minutes reach midnight; 10 minutes more reach 12:10 a.m. on the next day.

Exit

2:25 p.m. — First reach 1:50 p.m. after walking, then add 35 minutes. Finish at 2:25 p.m..
9:15 a.m. — First reach 8:20 a.m. after walking, then add 55 minutes. Finish at 9:15 a.m..
5:00 p.m. — First reach 4:25 p.m. after walking, then add 35 minutes. Finish at 5:00 p.m..

Practice A

1 min 15 s — Group the 75 seconds into complete 60-second minutes, then count the 15 remaining seconds.
75 min — Count from 12:35 p.m. to the next whole hour, then onward to 1:50 p.m.. The intervals add to 75 minutes.
1 weeks 5 days — One week is seven days. 12 = 7 × 1 + 5.
90 min — Count from 4:35 p.m. to the next whole hour, then onward to 6:05 p.m.. The intervals add to 90 minutes.
125 min — Each hour is 60 minutes. 2 × 60 + 5 = 125 minutes.
50 min — Count from 9:50 a.m. to the next whole hour, then onward to 10:40 a.m.. The intervals add to 50 minutes.
2 h 35 min — There are 2 full groups of 60 minutes and 35 more minutes.
50 min — Count from 12:45 p.m. to the next whole hour, then onward to 1:35 p.m.. The intervals add to 50 minutes.
95 s — Each minute contains 60 seconds. 1 × 60 + 35 = 95 seconds.
90 min — Count from 12:20 p.m. to the next whole hour, then onward to 1:50 p.m.. The intervals add to 90 minutes.
3 min 35 s — Group the 215 seconds into complete 60-second minutes, then count the 35 remaining seconds.
35 min — Count from 7:40 a.m. to the next whole hour, then onward to 8:15 a.m.. The intervals add to 35 minutes.
3 weeks 0 days — One week is seven days. 21 = 7 × 3 + 0.
135 min — Count from 9:30 a.m. to the next whole hour, then onward to 11:45 a.m.. The intervals add to 135 minutes.
285 min — Each hour is 60 minutes. 4 × 60 + 45 = 285 minutes.
110 min — Count from 7:50 a.m. to the next whole hour, then onward to 9:40 a.m.. The intervals add to 110 minutes.
Next day at 12:40 a.m. — 10 minutes reach midnight; 40 minutes more reach 12:40 a.m. on the next day.
255 minutes — Each hour has 60 minutes, so 4 hours 15 minutes is 240+15=255 minutes.

Practice B

75 s — Each minute contains 60 seconds. 1 × 60 + 15 = 75 seconds.
65 min — Count from 1:25 p.m. to the next whole hour, then onward to 2:30 p.m.. The intervals add to 65 minutes.
4:40 p.m. — Add 50 minutes to the start time, crossing each next hour carefully. 3:50 p.m. plus 50 minutes is 4:40 p.m..
50 min — Count from 11:40 p.m. to the next whole hour, then onward to 12:30 a.m.. The intervals add to 50 minutes.
3:50 p.m. — First reach 3:05 p.m. after walking, then add 45 minutes. Finish at 3:50 p.m..
4 min 35 s — Group the 275 seconds into complete 60-second minutes, then count the 35 remaining seconds.
35 min — Count from 11:40 a.m. to the next whole hour, then onward to 12:15 p.m.. The intervals add to 35 minutes.
3:10 p.m. — Add 35 minutes to the start time, crossing each next hour carefully. 2:35 p.m. plus 35 minutes is 3:10 p.m..
90 min — Count from 11:40 p.m. to the next whole hour, then onward to 1:10 a.m.. The intervals add to 90 minutes.
11:45 a.m. — First reach 10:50 a.m. after walking, then add 55 minutes. Finish at 11:45 a.m..
4 weeks 0 days — One week is seven days. 28 = 7 × 4 + 0.
135 min — Count from 2:05 p.m. to the next whole hour, then onward to 4:20 p.m.. The intervals add to 135 minutes.
11:30 a.m. — Add 25 minutes to the start time, crossing each next hour carefully. 11:05 a.m. plus 25 minutes is 11:30 a.m..
65 min — Count from 11:35 a.m. to the next whole hour, then onward to 12:40 p.m.. The intervals add to 65 minutes.
9:35 a.m. — First reach 8:40 a.m. after walking, then add 55 minutes. Finish at 9:35 a.m..
165 min — Each hour is 60 minutes. 2 × 60 + 45 = 165 minutes.
Next day at 12:20 a.m. — 20 minutes reach midnight; 20 minutes more reach 12:20 a.m. on the next day.
375 minutes — Each hour has 60 minutes, so 6 hours 15 minutes is 360+15=375 minutes.

Chapter Review

4 weeks 3 days — One week is seven days. 31 = 7 × 4 + 3.
25 min — Count from 12:45 p.m. to the next whole hour, then onward to 1:10 p.m.. The intervals add to 25 minutes.
11:20 a.m. — Add 35 minutes to the start time, crossing each next hour carefully. 10:45 a.m. plus 35 minutes is 11:20 a.m..
65 min — Count from 11:15 p.m. to the next whole hour, then onward to 12:20 a.m.. The intervals add to 65 minutes.
8:10 a.m. — First reach 7:15 a.m. after walking, then add 55 minutes. Finish at 8:10 a.m..
95 min — Each hour is 60 minutes. 1 × 60 + 35 = 95 minutes.
25 min — Count from 9:10 a.m. to the next whole hour, then onward to 9:35 a.m.. The intervals add to 25 minutes.
10:55 a.m. — Add 90 minutes to the start time, crossing each next hour carefully. 9:25 a.m. plus 90 minutes is 10:55 a.m..
90 min — Count from 11:15 p.m. to the next whole hour, then onward to 12:45 a.m.. The intervals add to 90 minutes.
11:05 a.m. — First reach 10:10 a.m. after walking, then add 55 minutes. Finish at 11:05 a.m..
3 h 35 min — There are 3 full groups of 60 minutes and 35 more minutes.
65 min — Count from 12:55 p.m. to the next whole hour, then onward to 2:00 p.m.. The intervals add to 65 minutes.
8:35 a.m. — Add 25 minutes to the start time, crossing each next hour carefully. 8:10 a.m. plus 25 minutes is 8:35 a.m..
75 min — Count from 10:50 a.m. to the next whole hour, then onward to 12:05 p.m.. The intervals add to 75 minutes.
8:25 a.m. — First reach 7:30 a.m. after walking, then add 55 minutes. Finish at 8:25 a.m..
65 s — Each minute contains 60 seconds. 1 × 60 + 5 = 65 seconds.
25 min — Count from 1:50 p.m. to the next whole hour, then onward to 2:15 p.m.. The intervals add to 25 minutes.
12:05 p.m. — Add 25 minutes to the start time, crossing each next hour carefully. 11:40 a.m. plus 25 minutes is 12:05 p.m..
110 min — Count from 11:35 a.m. to the next whole hour, then onward to 1:25 p.m.. The intervals add to 110 minutes.
2:10 p.m. — First reach 1:35 p.m. after walking, then add 35 minutes. Finish at 2:10 p.m..
1 min 25 s — Group the 85 seconds into complete 60-second minutes, then count the 25 remaining seconds.
50 min — Count from 1:50 p.m. to the next whole hour, then onward to 2:40 p.m.. The intervals add to 50 minutes.
3:05 p.m. — Add 50 minutes to the start time, crossing each next hour carefully. 2:15 p.m. plus 50 minutes is 3:05 p.m..
65 min — Count from 11:40 p.m. to the next whole hour, then onward to 12:45 a.m.. The intervals add to 65 minutes.
Next day at 12:30 a.m. — 15 minutes reach midnight; 30 minutes more reach 12:30 a.m. on the next day.
435 minutes — Each hour has 60 minutes, so 7 hours 15 minutes is 420+15=435 minutes.

Practice Exam

110 min — The suggested answer is not correct. Count from 11:15 p.m. to the next whole hour, then onward to 1:05 a.m.. The intervals add to 110 minutes. (3 points: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.)
135 min — Count from 10:55 a.m. to the next whole hour, then onward to 1:10 p.m.. The intervals add to 135 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
90 min — Count from 11:35 a.m. to the next whole hour, then onward to 1:05 p.m.. The intervals add to 90 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
245 s — Each minute contains 60 seconds. 4 × 60 + 5 = 245 seconds. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
8:05 a.m. — The suggested answer is not correct. First reach 7:20 a.m. after walking, then add 45 minutes. Finish at 8:05 a.m.. (3 points: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.)
90 min — Count from 10:50 a.m. to the next whole hour, then onward to 12:20 p.m.. The intervals add to 90 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
5:25 p.m. — Add 35 minutes to the start time, crossing each next hour carefully. 4:50 p.m. plus 35 minutes is 5:25 p.m.. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
8:15 a.m. — Add 50 minutes to the start time, crossing each next hour carefully. 7:25 a.m. plus 50 minutes is 8:15 a.m.. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
11:05 a.m. — The suggested answer is not correct. First reach 10:30 a.m. after walking, then add 35 minutes. Finish at 11:05 a.m.. (3 points: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.)
110 min — Count from 11:40 p.m. to the next whole hour, then onward to 1:30 a.m.. The intervals add to 110 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
1 h 10 min — There are 1 full groups of 60 minutes and 10 more minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
9:25 a.m. — First reach 8:40 a.m. after walking, then add 45 minutes. Finish at 9:25 a.m.. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
50 min — The suggested answer is not correct. Count from 11:15 p.m. to the next whole hour, then onward to 12:05 a.m.. The intervals add to 50 minutes. (3 points: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.)
2:10 p.m. — Add 25 minutes to the start time, crossing each next hour carefully. 1:45 p.m. plus 25 minutes is 2:10 p.m.. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
90 min — Count from 4:05 p.m. to the next whole hour, then onward to 5:35 p.m.. The intervals add to 90 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
2 weeks 3 days — One week is seven days. 17 = 7 × 2 + 3. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
110 min — The suggested answer is not correct. Count from 6:10 a.m. to the next whole hour, then onward to 8:00 a.m.. The intervals add to 110 minutes. (3 points: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.)
185 min — Each hour is 60 minutes. 3 × 60 + 5 = 185 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
135 min — Count from 6:05 a.m. to the next whole hour, then onward to 8:20 a.m.. The intervals add to 135 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
12:30 p.m. — First reach 11:35 a.m. after walking, then add 55 minutes. Finish at 12:30 p.m.. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
3 min 5 s — The suggested answer is not correct. Group the 185 seconds into complete 60-second minutes, then count the 5 remaining seconds. (3 points: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.)
135 min — Count from 9:00 a.m. to the next whole hour, then onward to 11:15 a.m.. The intervals add to 135 minutes. (2 points: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.)
Next day at 12:10 a.m. — 25 minutes reach midnight; 10 minutes more reach 12:10 a.m. on the next day. (3 points: 1 point for the correct claim; 1 for a mathematical justification; 1 for a clear diagram, example, or relevant calculation when applicable.)
195 minutes — Each hour has 60 minutes, so 3 hours 15 minutes is 180+15=195 minutes. (3 points: 1 point for the correct claim; 1 for a mathematical justification; 1 for a clear diagram, example, or relevant calculation when applicable.)