Question

Here are 5 number cards 2 5 7 8 9 one of the cards is removes and the mean average of the remaining four number cards is 6. Which card was removed? You must show your working

Answer 1

7

Explanation:

If one of the cards is removes and the mean average of the remaining four number cards is 6, then their sum is
`6\cdot 4=24.`

The sum of all five cards is

`2+5+7+8+9=31.`

Since
`31-24=7,` then the card with number 7 is removed.