Source: Previous Question Papers
The mean of 25, 18, x, 20, 17, 20, 21, 25 is 21. Find the value of x.
Options
Option A
24
Option B
20
Option C
23
Option D is correct
22
Explanation
The mean of a set of numbers is the sum of the numbers divided by the count of the numbers. Given numbers are 25, 18, x, 20, 17, 20, 21, 25. The count of numbers is 8. The mean is 21. Sum of numbers = 25 + 18 + x + 20 + 17 + 20 + 21 + 25 = 146 + x. So, (146 + x) / 8 = 21. Multiplying both sides by 8, we get 146 + x = 21 * 8 = 168. Therefore, x = 168 - 146 = 22.