Q&A - PSLE Math

[kancheongmum]

hi rrmummy thanks for the reply. I know of this thread but hit the wrong button and I start a new thread. Take this opportunity the thanks all parents and teachers who are willing to spend time to answer all the questions even the most challenging ones.

[Maths Monster]

kancheongmum:

hi all


appreciate help for this question
P6 Hokkien HK prelim paper Q15
a car n a coach travelled from town A to town B. The coach left Town A at 0648 and it took 5 hrs to reach Town B. The car started 30 mins later than the coach and it took 4 hours to reach Town B. At what time did the car catch up with the coach? (ANS 0918)

I have seen the answer somewhere but don't understand so can't explain to my son.

Thanks!

This is a \"catch up\" problem, ie how much time for a certain vehicle to catch up with another. In this case, the car need to catch up 30 mins of travel by the coach.

Coach took 5 hours to travel from A to B, this means in 30mins, the coach has traveled 0.5/5 x 100% = 10% of the total distance.

For each hour, the coach will travel 1/5 x 100% = 20% of the total distance and the car will travel 1/4 x 100% = 25%. This means that in 1 hour, the car will catch up with 25 - 20 = 5% distance of the coach.

It will take 10/5 = 2 hrs for the car to catch up with the coach. Therefore, it will time will be 2 hrs + 30 mins after 0648 => 0918

Check:
At 0918, the coach traveled 2.5 hrs, it has reached 2.5/5 x 100% = 50% of the total distance.

At 0918, the car traveled 2 hrs, it has reached 2/4 x 100% = 50% of the total distance => car has catch up with coach.

[kitty2]

Please help with this question,Thanks


A group of pupils sat for 2 tests,test A & test B.The number of pupils who failed test A was 1/7 of those who passed test A.

a) Given that there were 20 pupils who fialed test A,how many pupils passed test A?

b) The number of pupils who failed test B was 1/4 of those who failed test A.What fraction of the pupils passed test B?

[singmathstutor]

kitty2:

Please help with this question,Thanks


A group of pupils sat for 2 tests,test A & test B.The number of pupils who failed test A was 1/7 of those who passed test A.

a) Given that there were 20 pupils who fialed test A,how many pupils passed test A?

b) The number of pupils who failed test B was 1/4 of those who failed test A.What fraction of the pupils passed test B?

a) Fail: 1u, Pass: 7u
1u-->20
7u-->7x20=140
140 pupils passed test A (ans)

b) 1/4x20=5
5 pupils failed test B
total number of pupils = 20+140=160 (from part a)
number of pupils who passed test B = 160-5=155
fraction of pupils who passed test B = 155/160 = 31/32 (ans)

[happyluckymom]

Can someone help me solve Rosyth 2008 prelim maths paper last question number 47?

[kitty2]

singmathstutor:

kitty2:

Please help with this question,Thanks


A group of pupils sat for 2 tests,test A & test B.The number of pupils who failed test A was 1/7 of those who passed test A.

a) Given that there were 20 pupils who fialed test A,how many pupils passed test A?

b) The number of pupils who failed test B was 1/4 of those who failed test A.What fraction of the pupils passed test B?

a) Fail: 1u, Pass: 7u
1u-->20
7u-->7x20=140
140 pupils passed test A (ans)

b) 1/4x20=5
5 pupils failed test B
total number of pupils = 20+140=160 (from part a)
number of pupils who passed test B = 160-5=155
fraction of pupils who passed test B = 155/160 = 31/32 (ans)

:thankyou:

[singmathstutor]

kitty2:

singmathstutor:

[quote=\"kitty2\"]Please help with this question,Thanks


A group of pupils sat for 2 tests,test A & test B.The number of pupils who failed test A was 1/7 of those who passed test A.

a) Given that there were 20 pupils who fialed test A,how many pupils passed test A?

b) The number of pupils who failed test B was 1/4 of those who failed test A.What fraction of the pupils passed test B?

a) Fail: 1u, Pass: 7u
1u-->20
7u-->7x20=140
140 pupils passed test A (ans)

b) 1/4x20=5
5 pupils failed test B
total number of pupils = 20+140=160 (from part a)
number of pupils who passed test B = 160-5=155
fraction of pupils who passed test B = 155/160 = 31/32 (ans)

:thankyou:[/quote]You're welcome, kitty

[Muffins]

Got a question for you guys to answer. It's from a primary school test paper. I need the working in models, if you don't mind...


In a conference, there were some men and women. In the first day, there were 80 less women than men. In the second day, the number of men who came decreased by 10%, and the number of women who had arrived increased by 20%. The total number of people who had arrived for the second day was 1542.

How many men and women were there for the first and second day?

TIA.

[Maths Monster]

Muffins:

Got a question for you guys to answer. It's from a primary school test paper. I need the working in models, if you don't mind...


In a conference, there were some men and women. In the first day, there were 80 less women than men. In the second day, the number of men who came decreased by 10%, and the number of women who had arrived increased by 20%. The total number of people who had arrived for the second day was 1542.

How many men and women were there for the first and second day?

TIA.

Using Model:

Let 10u be the number of women on day 1

Day 1:
M [10u] [80]
W [10u]

Day 2: In the second day, the number of men who came decreased by 10%, and the number of women who had arrived increased by 20%.
M [9u] [72]
W [12u]

The total number of people who had arrived for the second day was 1542. We can write:
9u + 72 + 12u = 1542
u = 70


On Day 1, there were 780 men and 700 women.
On Day 2, there were 702 men and 840 women.

Check:
Day 1 to Day 2:
Men 780 to 702 => 10% decrease
Women 700 to 840 => 20% increase
Total came on Day 2 = 702 + 840 = 1542

[tianzhu]

Hi muffins

Hope this helps.

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Best wishes