PSLE
Ben and Vaidev have the same total number of coins. Ben has a number of twenty-cent coins and 55 ten-cent coins. The total mass of his coins is 0.637 kg. Vaidev has a number of twenty-cent coins and 115 ten-cent coins.

1. Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
2. Each twenty-cent coin is 1.4 g heavier than each ten-cent coin. What is the total mass of Vaidev's coins in kg?

(a)
Since Ben has less ten-cent coins than Vaidev but both had the same number of coins, Ben had more money.

Both boys have the same number of coins. Since Ben has less ten-cent coins than Vaidev, it means that Ben has more twenty-cent coins than Vaidev. So Ben has more money.

Difference in the number of ten-cent coins.
= 115 - 55
= 60

Difference in the value of 1 ten-cent coin and 1 twenty-cent coin
= 20 - 10
= 10¢

Amount that Ben had more than Vaidev
= 60 x 10
= 600¢
= $6

(b)
Difference in the mass between 60 ten-cent coins and 60 twenty-cent coins
= 60 x 1.4
= 84 g
= 0.084 kg

Total mass of Vaidev's coins
= 0.637 - 0.084
= 0.553 kg

Answer(s): (a) Ben, $6; (b) 0.553 kg