PSLE
Cody and Ben have the same total number of coins. Cody has a number of ten-cent coins and 30 five-cent coins. The total mass of his coins is 0.623 kg. Ben has a number of ten-cent coins and 70 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 3.4 g heavier than each five-cent coin. What is the total mass of Ben's coins in kg?

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

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

Difference in the number of five-cent coins.
= 70 - 30
= 40

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

Amount that Cody had more than Ben
= 40 x 5
= 200¢
= $2

(b)
Difference in the mass between 40 five-cent coins and 40 ten-cent coins
= 40 x 3.4
= 136 g
= 0.136 kg

Total mass of Ben's coins
= 0.623 - 0.136
= 0.487 kg

Answer(s): (a) Cody, $2; (b) 0.487 kg