PSLE
Bobby and Jenson have the same total number of coins. Bobby has a number of fifty-cent coins and 35 twenty-cent coins. The total mass of his coins is 0.854 kg. Jenson has a number of fifty-cent coins and 85 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 1.9 g heavier than each twenty-cent coin. What is the total mass of Jenson's coins in kg?

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

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

Difference in the number of twenty-cent coins.
= 85 - 35
= 50

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

Amount that Bobby had more than Jenson
= 50 x 30
= 1500¢
= $15

(b)
Difference in the mass between 50 twenty-cent coins and 50 fifty-cent coins
= 50 x 1.9
= 95 g
= 0.095 kg

Total mass of Jenson's coins
= 0.854 - 0.095
= 0.759 kg

Answer(s): (a) Bobby, $15; (b) 0.759 kg