Question

4. The mean and standard deviation of 20 items is found to be 10 and 2 respectively. At the time
of checking, it was found that one item 8 was incorrect. Calculate mean and standard
deviation if: (i) the wrong item is omitted. (ii) it is replaced by 12.
[Ans. (1) X = 10.11, o =1.997; (ii) X = 10.2,0 = 1.99
Ex

Answer 1

Answer:

The mean and standard deviation of 20 observation are found to be 10 and 2 respectively. On rechecking it was found that an observation 8 was incorrect. Calculate the correct mean and standard deviation in each of the following cases :

(i) If wrong item is omitted

(ii) If it is replaced by 12