PSLE
Jack and Liam have the same total number of coins. Jack has a number of fifty-cent coins and 35 twenty-cent coins. The total mass of his coins is 1.379 kg. Liam has a number of fifty-cent coins and 55 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 3.2 g heavier than each twenty-cent coin. What is the total mass of Liam's coins in kg?

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

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

Difference in the number of twenty-cent coins.
= 55 - 35
= 20

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

Amount that Jack had more than Liam
= 20 x 30
= 600¢
= $6

(b)
Difference in the mass between 20 twenty-cent coins and 20 fifty-cent coins
= 20 x 3.2
= 64 g
= 0.064 kg

Total mass of Liam's coins
= 1.379 - 0.064
= 1.315 kg

Answer(s): (a) Jack, $6; (b) 1.315 kg