PSLE
Tim and Ben have the same total number of coins. Tim has a number of ten-cent coins and 42 five-cent coins. The total mass of his coins is 1.08 kg. Ben has a number of ten-cent coins and 62 five-cent coins.

1. Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
2. Each ten-cent coin is 1.4 g heavier than each five-cent coin. What is the total mass of Ben's coins in kg?

(a)
Since Tim has less five-cent coins than Ben but both had the same number of coins, Tim had more money.

Both boys have the same number of coins. Since Tim has less five-cent coins than Ben, it means that Tim has more ten-cent coins than Ben. So Tim has more money.

Difference in the number of five-cent coins.
= 62 - 42
= 20

Difference in the value of 1 five-cent coin and 1 ten-cent coin
= 10 - 5
= 5¢

Amount that Tim had more than Ben
= 20 x 5
= 100¢
= $1

(b)
Difference in the mass between 20 five-cent coins and 20 ten-cent coins
= 20 x 1.4
= 28 g
= 0.028 kg

Total mass of Ben's coins
= 1.08 - 0.028
= 1.052 kg

Answer(s): (a) Tim, $1; (b) 1.052 kg