Q&A - PSLE Math

[fightingmom]

MathIzzzFun:

fightingmom:

Hi hi,


Can someone please help with the following 2 maths questions ...

(1) Varsha had some 20-cent and 50-cent coins.
7/8 of the coins were 20-cent coins and the rest were 50-cent coins.
After Varsha had spent $72.50 worth of 50-cent coins and 5/7 of the 20-cent
coins, she had 2/7 of the coins left.
Find the total amount of money Varsha left.

Thank you in advance !

Hi

Q1..

http://i43.tinypic.com/4ind4x.jpg\">

cheers.

=========================
Hi MathIzzzFun,

Thank you so much for your help! Sorry i take so long to reply cos facing some problem with my PC earlier on!

Once again, :thankyou:

[fightingmom]

small:

HTH for question 2...cheers!!


J : K : L
640-9U : 5U : 4U -> x 2
640-18U : 10U : 8U (at first)


After James and KEith had each lost half of their toy cars,the ratio become:
320 - 9U : 5U : 8U (after)


Given Keith had 100 more toy cars than James after they lost half their toy cars.
5U - 100 = 320 - 9U
14U = 420
1U = 30

James had 640-9U at first
= 640 - 9U
= 640 - 540
= 100

James had 100 toys cars at first

Hi Hi,

Just want to thank you for helping me solve the above question! So glad that i can find so many gurus here ! :rahrah:

Once again, :thankyou:

[anneshirleygilbert]

When Mike’s age was twice Kok Hwa’s age, Bala’s age was 21. Given that Mike was the oldest among the three persons, find Bala’s age when Mike was 62 years old.


Case 2
Bala ----- 21
KH ----- 21 + 1 unit
Mike ------ (21 + 1 unit) + (21 + 1 unit)
Difference in age between Mike and KH ----- 21 + 1 unit

Hello tianzhu,

Thank you for your prompt reply.

I am hung up on KH’s age being (21 + 1unit) when Bala was 21. Can you please help?

Thank you.

[tianzhu]

anneshirleygilbert:

I am hung up on KH's age being (21 + 1unit) when Bala was 21. Can you please help?

Hi anneshirleygilbert

Good Morning.

Don’t worry too much about it now.

Please go out and enjoy your wan ton mee first.

I’ll find time to draw the MD, most probably after twelve today.

Best wishes

[small]

anneshirleygilbert:

When Mike's age was twice Kok Hwa's age, Bala's age was 21. Given that Mike was the oldest among the three persons, find Bala's age when Mike was 62 years old.


Case 2
Bala ----- 21
KH ----- 21 + 1 unit
Mike ------ (21 + 1 unit) + (21 + 1 unit)
Difference in age between Mike and KH ----- 21 + 1 unit

Hello tianzhu,

Thank you for your prompt reply.

I am hung up on KH's age being (21 + 1unit) when Bala was 21. Can you please help?

Thank you.

Hi anneshirleygilbert,

Hope this helps.

The key point is Difference in age between two people remains the same

From case 1, we knew that the different in age between Bala and Kok Hwa is 1 unit;
so for case 2, when Bala is 21, Kok Hwa is 21 + 1 unit

[tianzhu]

Hi anneshirleygilbert


“Age Questions\" are popular in primary school maths.

Before putting pen to paper, students should realise that the difference in age between two people will always remain the same.

I am hung up on KH's age being (21 + 1unit) when Bala was 21. Can you please help?

Bala's age is 1u
KH's age is 2u

Difference in age ----- 1u

This difference remains the same.

So when Bala was 21, KH was (21+1u) as shown in the MD.

Usually two scenarios are given, current and some years ago or some years later.

You may work using MD or UM.

As usual, I’ve drawn more MD than it is necessary, try to get your child to understand the logic and consolidate the steps.

Have a happy weekend.

Best wishes.

http://farm8.staticflickr.com/7067/6854267621_b1022b156e_z.jpg\">

[anneshirleygilbert]

Oh, now I see… Kok Hwa’s age is not always twice Bala’s… that’s why he is not 21x2=42 years old, but 21yrs +1unit.


Thanks, tianzhu, for all your help. No won ton mee, not even oats, could go down my throat till this bone is cleared.

Thanks, too, small. Appreciate your help.

Thanks, too, to all the parents who have contributed so much on this forum. You just don’t know how much I’ve benefitted from all your unselfish sharing.

Most sincerely,
Anne

[Winx5015]

Hi pixiedust,


Thanks for helping.

Have a wonderful weekends!

Cheers!

[underthesea]

In a school's Community Involvement Project (CIP), each pupil who participates in any CIP activity will be awarded with CIP points as shown in the table below:


CIP Activities --------------------- Points Awarded
Seashore Cleaning ----------------------- 6
Charity Sale ------------------------------ 5
Recycling Project ------------------------ 4

1/4 of the pupils participated in Seashore Cleaning, 3/5 of the remainder pupils took part in Charity Sale and the rest of the pupils participated in the school's Recycling Project. A total of 4950 points was awarded. How many pupils took part in all three CIP activities?

Anything wrong with this question? I don't see there's any overlapping.

TIA.

[small]

underthesea:

In a school's Community Involvement Project (CIP), each pupil who participates in any CIP activity will be awarded with CIP points as shown in the table below:


CIP Activities --------------------- Points Awarded
Seashore Cleaning ----------------------- 6
Charity Sale ------------------------------ 5
Recycling Project ------------------------ 4

1/4 of the pupils participated in Seashore Cleaning, 3/5 of the remainder pupils took part in Charity Sale and the rest of the pupils participated in the school's Recycling Project. A total of 4950 points was awarded. How many pupils took part in all three CIP activities?

Anything wrong with this question? I don't see there's any overlapping.

TIA.

Hi underthesea,

HTH..


Points Awarded
Seashore Cleaning : Charity Sale : Recycling Project
6 : 5 :4

Number of pupils
Seashore Cleaning ----------------------- 5U
Charity Sale ------------------------------ 9U
Recycling Project ------------------------ 6U

total points
Seashore Cleaning ----------------------- 5U x 6 = 30U
Charity Sale ------------------------------ 9U x 5 = 45U
Recycling Project ------------------------ 6U x 4 = 24U

99U = 4950
1U = 4950 / 99
1U = 50

Total number of pupils ----- 20U
= 20 x 50
= 1000

1000 pupils took part in all three CIP activities