+0

# help

+1
83
2

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?

Jun 23, 2020

#1
+307
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.

Jun 23, 2020
#2
+131
+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 $$19=x$$.

Jun 23, 2020