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?
+310 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.
+131 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 \(19=x\).
