Question

In an experiment with 15 observations of x the following results were available `sum x^2=2830 sum x=170` one observation that was 20 was found to be wrong and it was replaced by its correct value of 30 Then the corrected variance is (1) `8.33` (2) `78` (3) `188.66` (4) `177.33`

Answer 1

`V=sumx^2/n-(sumx/n)^2`
`sumx^2=2830,sumx=170`
Increase in`sumx^2=900-400=500`
Incerase in`sumx=10`
`sumx^2=2830+500=3330`
`sumx=180`
n=15
`V=3330/15-(180/15)^2`
`V=222-144=78`.