Three of four numbers have a sum of 22. If the average of the four numbers is 8. Find the fourth number.
Answer: The fourth number is 10.
Let's understand the solution.
Let the four numbers be a, b, c and d.
According to the given information, we have two equations:
⇒ Average of a, b, c and d is 8: (a + b + c + d) / 4 = 8 (equation 1)
⇒ Sum of a, b, c is 22: (a + b + c) = 22 (equation 2)
We need to determine the value of d.
We can rewrite equation 1 as (a + b + c + d) = 32.
Now, substitute the value of equation 2 into equation 1:
⇒ (a + b + c) + d = 32
⇒ 22 + d = 32
⇒ d = 10