# Thread: SAT math question (averages)

1. ## SAT math question (averages)

Each of 5 people had a blank card on which they wrote a positive integer. If the average (arithmetic mean) of these integers is 15, what is the greatest possible integer that could be on one of the cards?

I know that the total sum of these integers is 75, because 5 * 15 = 75; but I don't know what to do from here.

2. Originally Posted by Pn0yS0ld13r
Each of 5 people had a blank card on which they wrote a positive integer. If the average (arithmetic mean) of these integers is 15, what is the greatest possible integer that could be on one of the cards?

I know that the total sum of these integers is 75, because 5 * 15 = 75; but I don't know what to do from here.
The average is in real, not integer, terms, so there is a difference between 15 and 15.2! Therefore, taking four other cards at the lowest value (let's assume that is 1), then we have:

$\frac{X+4}{5}=15$

Solving for X gives us 71.