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.

Wednesday, February 10, 2010

Ai Tong Sch 2009 P6 CA1 Math Paper 2 Q17

75% of the children in the stadium were girls. After 52 girls and 4 boys left, the remaining children formed groups of 8. In each group, there were 3 boys. How many children were there in the stadium at first?

Solution


Note - "Before" for girls is 3 parts, while "Before" for boys is 1 part. This is to represent 75% girls and 25% boys, before 52 girls and 4 boys left.

From the table above
4 units --> 40
1 unit --> 40 divided by 4 = 10

Total boys (after)
3 units --> 3 x 10 = 30

Total girls (after)
5 units --> 5 x 10 = 50

Total children (after)
30 + 50 = 80

Total children at first
80 + 52 + 4 = 136

Answer: 136 children

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