PSLE
Ethan and Oliver have the same total number of coins. Ethan has a number of twenty-cent coins and 33 ten-cent coins. The total mass of his coins is 1.056 kg. Oliver has a number of twenty-cent coins and 83 ten-cent coins.

1. Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
2. Each twenty-cent coin is 3.2 g heavier than each ten-cent coin. What is the total mass of Oliver's coins in kg?

(a)
Since Ethan has less ten-cent coins than Oliver but both had the same number of coins, Ethan had more money.

Both boys have the same number of coins. Since Ethan has less ten-cent coins than Oliver, it means that Ethan has more twenty-cent coins than Oliver. So Ethan has more money.

Difference in the number of ten-cent coins.
= 83 - 33
= 50

Difference in the value of 1 ten-cent coin and 1 twenty-cent coin
= 20 - 10
= 10¢

Amount that Ethan had more than Oliver
= 50 x 10
= 500¢
= $5

(b)
Difference in the mass between 50 ten-cent coins and 50 twenty-cent coins
= 50 x 3.2
= 160 g
= 0.16 kg

Total mass of Oliver's coins
= 1.056 - 0.16
= 0.896 kg

Answer(s): (a) Ethan, $5; (b) 0.896 kg