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Sunday, August 22, 2010

RGS Primary 2009 PSLE Math Prelim Paper 2 Q18

At first, 25% of Kumar's money was the same as 33 and 1/3 % of Lily's money. Lily's father gave her \$80 later, while Kumar spent \$325. In the end, Lily had 2 and 1/2 times as much money as Kumar.
a) How much money did Kumar have at first?
b) How much money did Lily have in the end?

Solution (Kumar) 4 units --> 2 parts + 325 (x5)**
(Lily) 3 units + 80 --> 5 parts (x2)**

**Kumar (x5) and Lily (x2) to make both of them 10 equal parts each.

(K) 20 units --> 10 parts + 1625
(L) 6 units + 160 --> 10 parts

(K) 20 units --> 10 parts + 1625
(L) 6 units --> 10 parts - 160

(K) - (L)
20 units - 6 units --> 10 parts - 10 parts + 1625 - (-160)
14 units --> 1625 + 160
14 units --> 1785
1 unit --> 1785 divided by 14 = 127.5

(a)
Kumar at first
4 units --> 4 x 127.5 = 510

(b)
Lily in the end
--> 3 units + 80
(3 x 127.5) + 80
= 382.5 + 80
= 462.5