RGS Primary 2009 PSLE Math Prelim Paper 2 Q11

Mrs Kee baked some cookies and packed all the cookies in 12 small boxes and 5 big boxes. There were equal number of cookies in each small box and equal number of cookies in each big box. Each big box contained 14 more cookies than each small box. 18/29 of the cookies baked were packed in small boxes. How many cookies were there in each small box?

Solution

12 small boxes --> 18/29 of cookies
1 small box --> 18/29 divided by 12
= 3/58 of cookies

5 big boxes --> 11/29 of cookies (29/29 - 18/29)
1 big box --> 11/29 divided by 5
= 11/145 of cookies

There were 14 more cookies in each big box than in each small box
11/145 - 3/58 --> 14 cookies
7/290 --> 14 cookies
1/290 --> 14 divided by 7 = 2

(Small box) 3/58 --> 15/290
15/290 --> 15 x 2 = 30

Answer: 30 cookies

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