Question

The average age three people running for election is 42. A fourth person joins the race and the average drops to 40. What is the fourth person’s age?

Answer 1

Call the four people
`a, b, c` and
`d`.

We know:

`(a+b+c)/(3)=42`

and

`(a+b+c+d)/(4)=40`

Thus:

`a+b+c=126`

`(126+d)/(4)=40`

`126+d=160`

`d=34`