Question

The mean of 50 observations was 250 it was detected on checking that the value of 165 was wrongly copied as 115 find the coreect mean

Answer 1

mean of 50 observation is 250

so the sum of 50 observations is

= 250 × 50

= 12500

wrong observation is 115

so sum of 49 observations is

12500 - 115

= 12385

sum of 50 observations with correct observation is 12385 + 165

= 12450

correct mean = 12450/ 50

= 1245/5

= 249

so the correct mean is 249