/ Maths question of the week (with answer)

The following maths question came out in the recent Singapore Primary School Leaving Examination (PSLE) which are for 12- years-old.

NB: You cannot use algebra to solve the question, only via arithmetic methods.

Shop A has 156kg of rice. Shop B has 72kg of rice.

After both shops sold an equal amount of rice, the ratio of rice that shop A has to that of shop B is 4:1.

Find the amount of rice sold by the shops.


So far the only method I could come up with is to start using the 4:1 ratio.

You can start listing all multiples of 4:1, 8:2, 12:3 to a max of 156:39 and you start subtracting from the original amounts till you get the difference to be equal.

When you come to 112:28, 156-112=44 and 72-28=44, hence the answer is 44kg.

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