Question

The average age of the ten people on my basketball team was 13.5, but then a 15-year-old joined our team and an 11-year-old quit the team. What is the average age of my team

now?

Answer 1

13.9

Explanation:

So the average can be defined as:
`average=(sum)/(amount)` and in this context, the sum is the sum of ages on the team, and the amount is the amount players, which is 10.

So to find the sum of people, we simply multiply the average by the amount:
`13.5*10=sum\implies135=sum`

Since a 15 year old joined, the new sum is now:
`135+15=150` and the new amount is:
`10+1=11`

An 11 year old quit, so now the sum is:
`150-11=139` and the new amount is:
`11-1=10`

Now let's take the new sum and amount to find the average:
`average=(139)/(10)\implies average=13.9`