The average of 10 numbers is 10. If a number is excluded from this set, then the new average becomes 9.

What is the value of the number that was excluded?

Guest Jun 23, 2020

#1**0 **

The sum of the numbers is 10x10=100. When we exclude a number x from this set, our new average is \(\frac{100-x}{9}\). We are told this equals 9. So our equation is \(\frac{100-x}{9}=9\).

Solve for x and you have your answer.

thelizzybeth Jun 23, 2020

#2**+1 **

If the average of 10 numbers is 10, the sum of the numbers is \(10*10 \) or 100. If we remove a number, we get the following equation:

\(\frac{100-x}{9} = 9\)

Now, we solve for \(x\):

\(\frac{100-x}{9} = 9\)

\(900 - 9x = 81\)

We divide one side by 9 which results to:

\(100 - x = 81 \)

\(100 - 81 = 19 \)

We get the final result which is \(19=x\).

Forgo Jun 23, 2020