PSLE
Andy and Flynn have the same total number of coins. Andy has a number of fifty-cent coins and 42 twenty-cent coins. The total mass of his coins is 1.454 kg. Flynn has a number of fifty-cent coins and 72 twenty-cent coins.

1. Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
2. Each fifty-cent coin is 2.4 g heavier than each twenty-cent coin. What is the total mass of Flynn's coins in kg?

(a)
Since Andy has less twenty-cent coins than Flynn but both had the same number of coins, Andy had more money.

Both boys have the same number of coins. Since Andy has less twenty-cent coins than Flynn, it means that Andy has more fifty-cent coins than Flynn. So Andy has more money.

Difference in the number of twenty-cent coins.
= 72 - 42
= 30

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

Amount that Andy had more than Flynn
= 30 x 30
= 900¢
= $9

(b)
Difference in the mass between 30 twenty-cent coins and 30 fifty-cent coins
= 30 x 2.4
= 72 g
= 0.072 kg

Total mass of Flynn's coins
= 1.454 - 0.072
= 1.382 kg

Answer(s): (a) Andy, $9; (b) 1.382 kg