PSLE Jeremy and Glen have the same total number of coins. Jeremy has a number of fifty-cent coins and 36 twenty-cent coins. The total mass of his coins is 0.7 kg. Glen has a number of fifty-cent coins and 66 twenty-cent coins.
- Who has less money in coins? How much less? Give your answers in this format. (Eg Adam, $12)
- Each fifty-cent coin is 2.8 g heavier than each twenty-cent coin. What is the total mass of Glen's coins in kg?
(a)
Both boys have the same number of coins. Since Glen has more twenty-cent coins than Jeremy, it means that Glen has less fifty-cent coins than Jeremy. So Glen has less 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 Glen had less than Jeremy
= 30 x 30
= 900¢
= $9
(b)
Difference in the mass between 30 twenty-cent coins and 30 fifty-cent coins
= 30 x 2.8
= 84 g
= 0.084 kg
Total mass of Glen's coins
= 0.7 - 0.084
= 0.616 kg
Answer(s): (a) Jeremy, $9; (b) 0.616 kg