PSLE
Julian and Fred have the same total number of coins. Julian has a number of fifty-cent coins and 57 twenty-cent coins. The total mass of his coins is 0.939 kg. Fred has a number of fifty-cent coins and 97 twenty-cent coins.

1. Who has less money in coins? How much less? Give your answers in this format. (Eg Adam, $12)
2. Each fifty-cent coin is 3.4 g heavier than each twenty-cent coin. What is the total mass of Fred's coins in kg?

(a)
Both boys have the same number of coins. Since Fred has more twenty-cent coins than Julian, it means that Fred has less fifty-cent coins than Julian.  So Fred has less money.

Difference in the number of twenty-cent coins.
= 97 - 57
= 40

Difference in the value of 1 twenty-cent coin and 1 fifty-cent coin
= 50 - 20
= 30¢

Amount that Fred had less than Julian
= 40 x 30
= 1200¢
= $12

(b)
Difference in the mass between 40 twenty-cent coins and 40 fifty-cent coins
= 40 x 3.4
= 136 g
= 0.136 kg

Total mass of Fred's coins
= 0.939 - 0.136
= 0.803 kg

Answer(s): (a) Julian, $12; (b) 0.803 kg