Chapter practice examination

Show your thinking; use diagrams when they help. Do not open solutions during your first attempt.

1. A1

   A student answers the following question with “111 min”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: How many minutes pass from 11:15 p.m. to 1:05 a.m.? (3 points)

   Reveal explanation

   Answer: 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.

   Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

2. A2

   How many minutes pass from 10:55 a.m. to 1:10 p.m.? (2 points)

   Reveal explanation

   Answer: 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.

   Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

3. A3

   How many minutes pass from 11:35 a.m. to 1:05 p.m.? (2 points)

   Reveal explanation

   Answer: 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.

   Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

4. A4

   Convert 4 min 5 s into seconds. (2 points)

   Reveal explanation

   Answer: 245 s

   Each minute contains 60 seconds. 4 × 60 + 5 = 245 seconds.

   Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

5. A5

   A student answers the following question with “9:05 a.m.”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A student leaves at 6:55 a.m., walks 25 minutes, then studies 45 minutes. At what time does studying end? (3 points)

   Reveal explanation

   Answer: 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..

   Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

6. A6

   How many minutes pass from 10:50 a.m. to 12:20 p.m.? (2 points)

   Reveal explanation

   Answer: 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.

   Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

7. A7

   A lesson begins at 4:50 p.m. and lasts 35 minutes. When does it finish? (2 points)

   Reveal explanation

   Answer: 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..

   Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

8. A8

   A lesson begins at 7:25 a.m. and lasts 50 minutes. When does it finish? (2 points)

   Reveal explanation

   Answer: 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..

   Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

9. A9

   A student answers the following question with “12:05 a.m.”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: A student leaves at 10:10 a.m., walks 20 minutes, then studies 35 minutes. At what time does studying end? (3 points)

   Reveal explanation

   Answer: 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..

   Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

10. A10

    How many minutes pass from 11:40 p.m. to 1:30 a.m.? (2 points)

    Reveal explanation

    Answer: 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.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

11. A11

    Express 70 minutes in hours and minutes. (2 points)

    Reveal explanation

    Answer: 1 h 10 min

    There are 1 full groups of 60 minutes and 10 more minutes.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

12. A12

    A student leaves at 8:25 a.m., walks 15 minutes, then studies 45 minutes. At what time does studying end? (2 points)

    Reveal explanation

    Answer: 9:25 a.m.

    First reach 8:40 a.m. after walking, then add 45 minutes. Finish at 9:25 a.m..

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

13. A13

    A student answers the following question with “51 min”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: How many minutes pass from 11:15 p.m. to 12:05 a.m.? (3 points)

    Reveal explanation

    Answer: 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.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

14. A14

    A lesson begins at 1:45 p.m. and lasts 25 minutes. When does it finish? (2 points)

    Reveal explanation

    Answer: 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..

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

15. A15

    How many minutes pass from 4:05 p.m. to 5:35 p.m.? (2 points)

    Reveal explanation

    Answer: 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.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

16. A16

    Express 17 days in weeks and days. (2 points)

    Reveal explanation

    Answer: 2 weeks 3 days

    One week is seven days. 17 = 7 × 2 + 3.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

17. A17

    A student answers the following question with “111 min”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: How many minutes pass from 6:10 a.m. to 8:00 a.m.? (3 points)

    Reveal explanation

    Answer: 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.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

18. A18

    Convert 3 h 5 min into minutes. (2 points)

    Reveal explanation

    Answer: 185 min

    Each hour is 60 minutes. 3 × 60 + 5 = 185 minutes.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

19. A19

    How many minutes pass from 6:05 a.m. to 8:20 a.m.? (2 points)

    Reveal explanation

    Answer: 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.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

20. A20

    A student leaves at 11:20 a.m., walks 15 minutes, then studies 55 minutes. At what time does studying end? (2 points)

    Reveal explanation

    Answer: 12:30 p.m.

    First reach 11:35 a.m. after walking, then add 55 minutes. Finish at 12:30 p.m..

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

21. A21

    A student answers the following question with “4 min 5 s”. Explain whether the answer is correct, then solve the question and justify your answer. Original question: Express 185 seconds in minutes and seconds. (3 points)

    Reveal explanation

    Answer: 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.

    Scoring: 1 point for identifying the given answer as incorrect; 1 for explaining the error; 1 for giving the corrected solution and appropriate units.

22. A22

    How many minutes pass from 9:00 a.m. to 11:15 a.m.? (2 points)

    Reveal explanation

    Answer: 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.

    Scoring: 1 point for a mathematically valid calculation/model, 1 point for the correct final answer with units when appropriate.

23. A23

    A trip begins at 11:35 p.m. and lasts 35 minutes. On which day does it finish and at what time? (3 points)

    Reveal explanation

    Answer: Next day at 12:10 a.m.

    25 minutes reach midnight; 10 minutes more reach 12:10 a.m. on the next day.

    Scoring: 1 point for the correct claim; 1 for a mathematical justification; 1 for a clear diagram, example, or relevant calculation when applicable.

24. A24

    Why is 3 hours 15 minutes not 315 minutes? (3 points)

    Reveal explanation

    Answer: 195 minutes

    Each hour has 60 minutes, so 3 hours 15 minutes is 180+15=195 minutes.

    Scoring: 1 point for the correct claim; 1 for a mathematical justification; 1 for a clear diagram, example, or relevant calculation when applicable.