The average of five numbers is $10.6$. Four of the numbers are 10, 4, 5 and 20. What is the value of the fifth number?
I need to find a number that makes the average of five numbers equal to 10.6. That means the sum of the five numbers divided by 5 is 10.6. So, the sum of the five numbers is 10.6 times 5, which is 53. I already know the sum of the first four numbers: 10 + 4 + 5 + 20, which is 39. So, the fifth number must be the difference between 53 and 39, which is 14. 