Question

The mean of 72, 78, 82, х, 75, 80, 72 is 77. Find the value of x.

Answer 1

Given: The mean of 72, 78, 82, x, 75, 80, 72 is 77.

Step-wise calculation:

1. Mean formula:

`"Mean" = "Sum of observations"/"Number of observations"`

2. Substitute values:

`77 = (72 + 78 + 82 + x + 75 + 80 + 72)/7`

3. Sum known numbers:

72 + 78 + 82 + 75 + 80 + 72

= 459

4. Multiply both sides by 7:

7 × 77 = 459 + x

⇒ 539 = 459 + x

5. Solve for x:

x = 539 – 459

= 80