This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

Friday, September 05, 2008

Catholic High Sch 2006 PSLE Math Prelim Q29

Alan has enough money to buy either 18 pencils or 15 pens. If he buys 12 pencils, how many pens can be buy with the remaining money?

Solution 

18 pencils ----- 15 pens 
(divided both by 3)

6 pencils ----- 5 pens

If he bought 12 pencils, it means he bought 6 pencils less. This amount of money is equivalent to the price of 5 pens. 

Answer: He could have bought 5 pens with the remaining money.

3 comments:

Fate said...

Dear Mr Song,
Understand that you are tied up during this crucial period. So, I posted this question not expecting any reply from you, but to borrow some space in your popular blog, hoping someone will pick it up.

Q) At a party, Sarah distributed 18 sweets to each of the boys and 20 sweets to each of the girls and had 48 sweets left. If she had distributed 20 sweets to each of the boys and 18 sweets to each of the girls instead, she would have 32 sweets left. If Sarah had 40 pupils in her class,

a) How many more boys than girls were there in her class?
b) How many sweets did she have at first?

If you seek an answer, set the question free. If you get it, it’ll benefit many. If you don’t get it, it wasn’t yours to begin with. Fate and destiny, it was meant to be.

Fate
Best Wishes

Fate said...

Dear Mr Song

You may wish to take a look at this problem when time permits.

Q) At a party, Sarah distributed 18 sweets to each of the boys and 20 sweets to each of the girls and had 48 sweets left. If she had distributed 20 sweets to each of the boys and 18 sweets to each of the girls instead, she would have 32 sweets left. If Sarah had 40 pupils in her class,

a) How many more boys than girls were there in her class?
b) How many sweets did she have at first?

IT said...

48 -32 = 16
16/2 = 8
There are 8 more boys
40-8= 32
32/2=16

There are 16 girls and 24 boys

16 x 18 + 24 x20 + 48 = 800

She had 800 sweets at first