Question

The mean of four observations is 10 and when a constant a is added to each observation, the mean becomes 13. The value of a is

Answer 1

Answer:

Search it in the ncert book

Step-by-step explanation:

Of class 9th

Answer 2

The value of a is 3

Step-by-step explanation:

$Mean = \frac{\text{Sum of all observations}}{\text{No. of observations}}$

The mean of four observations is 10

$10=\frac{\text{Sum of 4 observations}}{4}$

$40=\text{Sum of 4 observations}$

a is added to each observation

So, New sum = 40+4a

The mean becomes 13.

So, $13 = \frac{40+4a}{4}$

$13 \times 4 =40+4a$

52 = 40+4a

52-40=4a

12=4a

3=a

Hence The value of a is 3

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