PSLE
Rael and Ken have the same total number of coins. Rael has a number of fifty-cent coins and 57 twenty-cent coins. The total mass of his coins is 1.224 kg. Ken has a number of fifty-cent coins and 107 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 1.4 g heavier than each twenty-cent coin. What is the total mass of Ken's coins in kg?

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

Difference in the number of twenty-cent coins.
= 107 - 57
= 50

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

Amount that Ken had less than Rael
= 50 x 30
= 1500¢
= $15

(b)
Difference in the mass between 50 twenty-cent coins and 50 fifty-cent coins
= 50 x 1.4
= 70 g
= 0.07 kg

Total mass of Ken's coins
= 1.224 - 0.07
= 1.154 kg

Answer(s): (a) Rael, $15; (b) 1.154 kg