Question

If the mean of 2, 9, x + 6, 2x + 3, 5, 10, 5 is 7, then the value of x is ______.

विकल्प

• 9

• 6

• 5

• 3

Answer 1

If the mean of 2, 9, x + 6, 2x + 3, 5, 10, 5 is 7, then the value of x is 3.

Explanation:

The formula for the mean of a set of numbers is:

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

We are given the numbers:
2, 9, (x + 6), (2x + 3), 5, 10, 5
The mean is given as 7.

`(2 + 9 + (x + 6) + (2x + 3) + 5 + 10 + 5)/7 = 7`

Sum of all terms:

= 2 + 9 + x + 6 + 2x + 3 + 5 + 10 + 5

= (2 + 9 + 6 + 3 + 5 + 10 + 5) + (x + 2x)

= 40 + 3x

Now, using the mean formula:

`(40 + 3x)/7`

= 7

Multiply both sides by 7:

40 + 3x = 49

Subtract 40 from both sides:

3x = 9

x = `9/3`

x = 3