Question

The mean of 10 observations was calculated as 40. It was detected on rechecking that the value of 45 was wrongly copied as 15 . Find the correct mean

Answer 1

Solution :

The mean of 10 observations = 40

The sum of 10 observations = 40×10

= 400

If the observation 45 was wrongly

copied as 15 then

correct observation = 45 - 15

= 30

Sum of correct observations = 400+30

= 430

Correct mean = 430/10

= 43

Therefore ,

Correct mean = 43

•••••

Answer 2

Answer:

43

Step-by-step explanation:

Sum of the 10 observations:

Mean = 40

Sum = 10 x 40 = 400

Take away the wrongly calculated value:

400 - 15 = 385

Add back the correct value:

385 + 45 = 430

Find the correct mean:

Mean = 430 ÷ 10 = 43

Answer: The mean is 43