PSLE Vaidev and Rael have the same total number of coins. Vaidev has a number of fifty-cent coins and 36 twenty-cent coins. The total mass of his coins is 0.501 kg. Rael has a number of fifty-cent coins and 66 twenty-cent coins.
- Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
- Each fifty-cent coin is 1.6 g heavier than each twenty-cent coin. What is the total mass of Rael's coins in kg?
(a)
Since Vaidev has less twenty-cent coins than Rael but both had the same number of coins, Vaidev had more money.
Both boys have the same number of coins. Since Vaidev has less twenty-cent coins than Rael, it means that Vaidev has more fifty-cent coins than Rael. So Vaidev has more money.
Difference in the number of twenty-cent coins.
= 66 - 36
= 30
Difference in the value of 1 twenty-cent coin and 1 fifty-cent coin
= 50 - 20
= 30¢
Amount that Vaidev had more than Rael
= 30 x 30
= 900¢
= $9
(b)
Difference in the mass between 30 twenty-cent coins and 30 fifty-cent coins
= 30 x 1.6
= 48 g
= 0.048 kg
Total mass of Rael's coins
= 0.501 - 0.048
= 0.453 kg
Answer(s): (a) Vaidev, $9; (b) 0.453 kg