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, April 14, 2010

CHIJ St Nicholas Girls' Sch 2009 P6 SA1 Paper 2 Q3

Mr Ong had 5 kg or rice. After he sold 5/12 of it, he repacked the remaining rice into smaller packets of 2/3 kg each. How much rice had he left?

Solution

Used 5/12, had 7/12 left.
7/12 left --> 7/12 x 5 kg = 35/12 kg (35 twelfths kg)

Repacked this 35 twelfths kg into packets of 8 twelfths kg (2/3 kg --> 8/12 kg)
35 twelfths divided by 8 packets --> 4 wholes and 3 twelfths
3 twelfths (left unpacked) --> 3/12 --> 1/4 or 0.25

Answer: 1/4 kg or 0.25 kg left

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