PSLE Ryan and Jack have the same total number of coins. Ryan has a number of fifty-cent coins and 70 twenty-cent coins. The total mass of his coins is 0.758 kg. Jack has a number of fifty-cent coins and 90 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 2.8 g heavier than each twenty-cent coin. What is the total mass of Jack's coins in kg?
(a)
Since Ryan has less twenty-cent coins than Jack but both had the same number of coins, Ryan had more money.
Both boys have the same number of coins. Since Ryan has less twenty-cent coins than Jack, it means that Ryan has more fifty-cent coins than Jack. So Ryan has more money.
Difference in the number of twenty-cent coins.
= 90 - 70
= 20
Difference in the value of 1 twenty-cent coin and 1 fifty-cent coin
= 50 - 20
= 30¢
Amount that Ryan had more than Jack
= 20 x 30
= 600¢
= $6
(b)
Difference in the mass between 20 twenty-cent coins and 20 fifty-cent coins
= 20 x 2.8
= 56 g
= 0.056 kg
Total mass of Jack's coins
= 0.758 - 0.056
= 0.702 kg
Answer(s): (a) Ryan, $6; (b) 0.702 kg