Question

The mean of a group of 20 items was found to be 40. While checking it was found item 43 was wrongly written as 53 calculate the correct mean

Answer 1

Answer: 39.5.

Step-by-step explanation:

Mean of 20 items is 40.

Let sum of items be s.

s= 20*40 = 800.

Incorrect item = 53.

Correct item = 43.

Correct sum = (s-53) + 43= s - 10

= 800 - 10 = 790.

Correct mean = correct sum / 20

= 790 / 20

= 39.5.