This is the marking copy and it carries every answer. Her sheet is the other file — same numbering, same margin codes, so you can mark straight down the page.
Gupta boarded the bus at 11.40 a.m. The bus ride took 38 minutes. After alighting from the bus, he walked for 28 minutes from the bus stop to his school. What time did he reach his school? (Give your answer in 24-hour clock format.)
answer 1246
method Add the two journeys to 11.40 a.m. A bus ride of 38 min: 11.40 + 20 min reaches 12.00 noon, and 18 min more gives 12.18 p.m. Then walk 28 min: 12.18 + 28 min = 12.46 p.m. In 24-hour clock that is 1246.
watch Writing 0046 or 1146 by mishandling the crossing of 12 noon, or converting to 24-hour clock by adding 12 to a time that is already past noon.
David went to sleep at 21 50. He slept for 9 h 20 min. At what time did he wake up? (Give your answer in 24-hour clock format.)
answer 0710
method Add the hours first: 21 50 + 9 h = 30 50, which is past midnight, so take off 24 h to get 06 50 the next morning. Then add the 20 min: 06 50 + 20 min = 07 10.
watch Writing 30 50, or adding the minutes as if 50 + 20 made 70. Sixty minutes make an hour, so 50 + 20 rolls over into the next hour.
Sam spent a total of 3 h 10 min revising for his English, Science and Mathematics tests over the weekend. He spent 50 min on English and another 1 h 25 min on Science. How long did Sam spend revising Mathematics? Express your answer in minutes.
answer 55
method Change everything to minutes first. Total = 3 × 60 + 10 = 190 min. English = 50 min. Science = 60 + 25 = 85 min. Mathematics = 190 − 50 − 85 = 55 min.
watch Subtracting hours and minutes separately without converting, which turns 3 h 10 min − 1 h 25 min into a negative number of minutes.
Meena left her house to watch a movie at the cinema. Her watch showed 1630 but it was actually 5 minutes slower than the actual time. She took 35 minutes to reach the cinema. In the end, she was 10 minutes early for the movie. What time did the movie begin? Give your answer in 24-hour clock format.
answer 1720
method Her watch is 5 minutes SLOW, so the real time was 1630 + 5 = 1635. The journey took 35 minutes, so she arrived at 1635 + 35 = 1710. She was 10 minutes early, so the movie began 10 minutes after she arrived: 1710 + 10 = 1720.
watch Taking 5 minutes off instead of adding it. A slow watch shows a time EARLIER than the real one, so the real time is later.
Mariam started her piano lesson at the time shown on the clock (the minute hand points at 12 and the hour hand at 1, so 1 o’clock in the afternoon). The duration of the piano lesson is 75 minutes. However, the lesson ended 10 minutes later than that. What time did her lesson end? Give your answer in 24-hour clock format.
12
11 | 1
| /
10 | / 2
|/
9 * 3 minute hand: 12
hour hand: 1
8 4
7 6 5
the lesson starts at 13 00(A) 13 65 (B) 14 05 (C) 14 15 (D) 14 25
answer (D) — 14 25
method The clock reads 1 o’clock in the afternoon, which is 13 00. The lesson runs 75 minutes, which is 1 hour 15 minutes, so it was due to end at 13 00 + 1 h 15 min = 14 15. It actually ended 10 minutes after that: 14 15 + 10 min = 14 25.
watch Answering 14 15 and forgetting the extra 10 minutes, or writing 13 65 — there is no such time, because 60 minutes roll over into the next hour.
The clock shown below was 45 minutes behind the actual time. To set the clock to the correct time, how many 1/4-turn(s) must the minute hand be moved clockwise?
12
11 1
10 2
|
9 +----> 3 minute hand on 12
hour hand on 3
8 4
7 5
6(1) 1 (2) 2 (3) 3 (4) 4
answer (3) — 3
method A full turn of the minute hand is 60 minutes, so a 1/4-turn is 60 ÷ 4 = 15 minutes. The clock is 45 minutes behind, so the minute hand must go forward 45 minutes. 45 ÷ 15 = 3 quarter-turns.
watch Moving the hand 45 minutes and answering 45, or working with the hour hand instead of the minute hand.
The table shows the programme for the Children's Day celebration. What was the total duration of the Form Teachers' performances?
07 30 - 07 45 | Flag-raising ceremony 07 45 - 07 55 | Principal's speech 07 55 - 08 00 | Mass Singing 08 00 - 08 10 | Primary 4 Form Teachers' performance (Story-telling) 08 10 - 08 25 | Primary 5 Form Teachers' performance (Skit) 08 25 - 08 40 | Mass Singing 08 40 - 08 50 | Primary 6 Form Teachers' performance (Dance) 08 50 | End of concert
answer 35
method Pick out only the rows that say Form Teachers' performance. Primary 4: 08 00 to 08 10 = 10 min. Primary 5: 08 10 to 08 25 = 15 min. Primary 6: 08 40 to 08 50 = 10 min. Total = 10 + 15 + 10 = 35 min.
watch Including the Mass Singing from 08 25 to 08 40 because it sits between two performances, giving 50 min. It is not a Form Teachers' performance — the rows must be chosen by NAME, not by position.