PSLE John and Billy have the same total number of coins. John has a number of ten-cent coins and 50 five-cent coins. The total mass of his coins is 1.067 kg. Billy has a number of ten-cent coins and 90 five-cent coins.
- Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
- Each ten-cent coin is 3.3 g heavier than each five-cent coin. What is the total mass of Billy's coins in kg?
(a)
Since John has less five-cent coins than Billy but both had the same number of coins, John had more money.
Both boys have the same number of coins. Since John has less five-cent coins than Billy, it means that John has more ten-cent coins than Billy. So John has more money.
Difference in the number of five-cent coins.
= 90 - 50
= 40
Difference in the value of 1 five-cent coin and 1 ten-cent coin
= 10 - 5
= 5¢
Amount that John had more than Billy
= 40 x 5
= 200¢
= $2
(b)
Difference in the mass between 40 five-cent coins and 40 ten-cent coins
= 40 x 3.3
= 132 g
= 0.132 kg
Total mass of Billy's coins
= 1.067 - 0.132
= 0.935 kg
Answer(s): (a) John, $2; (b) 0.935 kg