Wednesday, June 8, 2011

June Vacation Chap 9.2 RATE (L5) Can he catch up with her?

Grace left home at 6.30 am to walk to school. 10 minutes later, her brother Shamus saw her wallet on the dining table. He grabbed the wallet and hopped onto his bicycle and rode after Grace.

Shamus rode his bicycle 3 times as fast as Grace walked.
Q1: What time was it when Shamus caught up with Grace?
Q2: If the school is 800m from home, did Shamus reach Grace before she arrived at school?

Use the following to guide you...
  • What information do you know from the problem?
  • What else do you need to know to solve the problem?
  • Pick a reasonable number for the information you need.


  1. 1) 6.45 am
    2) How fast/slow did Grace walk? 800m = meters not minutes as I know... So just in the 10 minutes Grace MAY HAVE already reached school...

  2. Possible scenario:
    2) And that 10 minutes MAY HAVE BEEN just walked down of the HDB as Lift = Out of Order(5 minutes), Walk to traffic light(2 minutes), help old lady cross road(1 minute), Wait for friend to go school together(1 minute), Walked for 1 minute(10 minutes in total and walked 400m in total)

  3. 1. 6.45 am
    2. It depends on the current situation that Grace was in. Grace could have been held up by the lift or the traffic light in those 10 minutes and not reach school yet. However, if Grace was not held up by anything, she could have easily reached school by that 10 minutes.

  4. Worst case scenario, anyone? XD

  5. 1. 6.45 am
    2. It all depends on the speed f Grace's walking. The average human walking speed is about 83.3m per minute. So if she had been walking for 10 minutes, she would have walked about 833 meters, which means she already reached the school.

  6. It was 6.45am.

    It depends on the situation. During the 10 minutes, Grace could have waited for the lift, took the lift and gone down. She could also have taken the stairs and this would take more time than taking the lift. There is also the possibility of traffic lights and maybe some other unforseen circumstances.

  7. 1. 6.45am
    2. there are a few possibilities. it could be that there are problems in the traffic for one which can cause grace to have reach the school first before shamus reach her because shamus was stuck in traffic, or the other way around.we also cannot throw away the possibility of when shamus reach her exactly when grace reach school

  8. 1. 6.45 am
    2. It depends on the situation both Shamus and grace are in. If both are in a traffic congested place, there is a possible chance Shamus can catch up to her in the stated speed but if one is faster and the other slower, Shamus, in both situation, might not catch up to Grace. It entirely depends in the situation they both individually are in.

  9. 1. 6:45

    2.The situation varies on the waiting time for the lift or time taken to walk down the staris, the time waited to cross the road is also included

  10. 1 - 6.45 am

    2 - It depends on Grace's speed and the situation they both are in.

  11. 1) 6.45am

    2) The speed which Grace walked could have allowed her to reach school first and there might be roads in between the journey which could delay Grace or Shamus

  12. 6.45am

    It depends on the speed Grace had taken to walk, wait for the lift, take the lift, traffic jam and other delays.

  13. 6.45 am.
    Shamus probably didn't reach Grace before she went to school because most people can walk 800m in ten minutes, it depends on the speed she was walking at and if she was delayed at all.

  14. 1) 6.45a.m.
    2)It would depend on how fast Grace is and based on any delays on the way to the school unless stated that there is no delays

  15. 6.45am
    In order for us to find out if Shamus had reached Grace before she had reached the school, 2 important information should be given. 1 : What was the rate of Grace's walking speed. 2 : Was Grace/Shamus moving in a constant rate? Hence, it is possible that Grace may or may not reach the school yet and Shamus may even catch up with her.

  16. Q1. 6.45am

    Q2. It depends on the speed Grace was walking at, if she had walked at a speed of 80m/min she would have reached school in the 10 minutes but if she had walked slower she might not have reached school yet. Another factor that may cause Grace to have not reached school yet is the condition of the surroundings(e.g a stoplight breaks down thus causing her to stop for a moment).

  17. Question 1:6.45am
    Question 2:It depends as Grace could have easily been held up at a traffic light as well as Grace's speed e.g taking a walk or brisk walking

  18. Q1)6:45a.m.
    Q2)Shamus:taking lift(about a minute),picking up the wallet(a minute gone),waiting for the traffic lights(5 minutes).Total:7 minutes waiting time
    Grace:waiting for traffic lights(5 minutes).Total 5 minutes waiting time.
    In this scenario,Shamus would have caught up with grace,as Shamus is 3 times faster than grace,but grace would have already reached the school,sothen again,the situation depends on the speed of the two people and the waiting time of them both.

  19. 1. 6.45 a.m.
    2. It depends on the speed of Grace, whether she was fast or slow. If she was fast(80m/min<), Shamus would probably not have cought up with Grace but if Grace was slow (60/min>) Shamus would probably reach her in time.