Q&A - PSLE Math

[corneyAmber]

Hv time for Q1 and Q2 first:


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[lizawa]

suiyuan:

Thank you for your time.



3) Terry walks to school at an average speed of 4km/h every day. One day, after walking a distance of 1km, he realised that his watch was slow. So, he ran at a constant speed and managed to reach the school just on time. Later, he calculated that if he had run at this speed right from the start of the journey, he would have reached school 5 minutes earlier. What was his running speed?

Time taken to walk 1km = 1/4 hr
Let the constant speed he ran be y km/h, remaining distance be x km
Time taken = x/y hr
Total time taken = (x/y + 1/4)hr

If he runs at this speed from beginning, time taken = (x+1) / y hr. This is 1/12 hr (or 5 min) faster.

(x+1) / y = (x/y+1/4) - 1/12
Solve this equation, the \"x\" will be eliminated and
y = 6km/h

[clover18]

Does anyone have feedback on Math program by Andrew Er or Learning Lab?

[AnnT2009]

[Moderator's note: Topics merged.]


Hi,
I chanced upon this website recently. Need help to solve this question,

Amy took 3 hours to travel from Town P to Town Q. Pansy took 2 hours to travel from Town Q to Town P. Both of them started travelling at 9am. At what time did they pass each other?

Thanks and happy new year.

[csc]

AnnT2009:

Hi,

I chanced upon this website recently. Need help to solve this question,

Amy took 3 hours to travel from Town P to Town Q. Pansy took 2 hours to travel from Town Q to Town P. Both of them started travelling at 9am. At what time did they pass each other?

Thanks and happy new year.

Let me try.

In 1 hour, Amy covered 1/3 of distance.
In 1 hour , Pansy covered 1/2 of distance

In 1 hour both covered 1/3 + 1/2 = 5/6 of distance

5/6 of distance ====== 1 hour
6/6 of distance ====== 1 1/5 hour = 1 hour 12 minutes

Therefore , they passed each other at 10.12 am.

Hope I'm right.

[AnnT2009]

Hi csc,


Your answer is the same as the assessment book.
A little confused, why your calculation is based on 6/6?
How to explain to kid?
Thanks for enlightening a rusty mind.

Thanks.

[csc]

As Amy and Pansy are travelling in the opposite direction, when they meet, they would have covered the total distance from P to Q. That explain the 6/6 - whole distance.


Hope it helps.

[AnnT2009]

Hi csc,


Sorry! Still confused, don’t they meet somewhere in the middle of the journey.

Thanks for your patience.

[3Boys]

csc:

AnnT2009:

Hi,

I chanced upon this website recently. Need help to solve this question,

Amy took 3 hours to travel from Town P to Town Q. Pansy took 2 hours to travel from Town Q to Town P. Both of them started travelling at 9am. At what time did they pass each other?

Thanks and happy new year.

Let me try.

In 1 hour, Amy covered 1/3 of distance.
In 1 hour , Pansy covered 1/2 of distance

In 1 hour both covered 1/3 + 1/2 = 5/6 of distance

5/6 of distance ====== 1 hour
6/6 of distance ====== 1 1/5 hour = 1 hour 12 minutes

Therefore , they passed each other at 10.12 am.

Hope I'm right.

Maybe I'm just old but I find this new way of doing math just completely crazy. :?

[tianzhu]

Maths Questions from http://www.channelnewsasia.com/discussion/forum.htm


1. Two sisters, Melissa and Nicole, started brisk-walking at 6.45a.m. from their house to a nearby park. Melissa walked at an average speed of 90m/min while Nicole's average speed was 60m/min. After arriving at the park, Melissa rested for 10 minutes and then walked back home. If Melissa met Nicole at 7.40 a.m. on her return journey, what was the distance between their house and the park?

2. A group of people met at a party. Each person shook hands with everyone else. Mr Li shook hands with 3 times as many men as women. Mrs Li shook hands with 4 times as many men as women. How many men and how many women were there at the party?