If the S.D. of a set of observations is 8 and if each observation is divided by `-2`, the S.D. of the new set of observations will be `(a) -4`             `(b) -8`              `(c) 8`          `(d) 4`

Explanation

It is known that if a set of observations with standard deviation `sigma`, are multiplied with a non-zero real number `a`, then standard deviation of the new observations will be `abs(a) sigma` .

So, by dividing the set of observation by `-2` is same as multiplying the observations by `frac{1}{-2}`.

So the new standard deviation becomes, `abs(frac{1}{-2})xx 8`

`=frac{8}{2}=4`