Raffles Girls Pri Sch 2007 PSLE Math Prelim Q46

At first, the ratio of the number of marbles received by John and Peter was 4:7. The ratio of the number of marbles received by Peter and Sam was 9:5. Then, John gave 1/12 of his marbles to Sam, and Peter gave 1/9 of his marbles to Sam. As a result, Sam had 135 marbles in the end.

(a) Find the ratio of the number of John’s marbles to the number of Sam’s marbles at first.

(b) Find the total number of marbles received by the 3 boys.

Solution


45 units ----- 135 (marbles)
1 unit ----- 135 divided by 45 = 3
134 units ----- 134 x 3 = 402

(a) Answer: 36 : 35
(b) Answer: 402 marbles