Please solve this question

Given:

Number of mice and frequency

Mean = 7

To find:

The value of x.

Solution:

Number of mice = X

Frequency = Y

XY = Multiply X and Y values.

X         Y            XY

5         4            20

6         13           78

7         16           112

8          x            8x

9          6            54

Sum of Y = 4 + 13 + 16 + x + 6

               = 39 + x

Sum of XY = 20 + 78 + 112 + 8x + 54

                  = 8x + 264

Mean formula:

Do cross multiplication.

Subtract 264 from both sides, we get

Subtract 7x from both sides, we get

The value of x is 9.