Answer 1

 4

If a set of observations, with SD \[\sigma\]  , are multiplied with a non-zero real number a, then SD of the new observations will be\[\left| a \right| \sigma .\]

Dividing the set of observations by − 2 is same as multiplying the observations by \[\frac{1}{- 2}\]

\[\text{ New}  S . D . = \left| - \frac{1}{2} \right| \times 8\]

\[ = \frac{8}{2}\]

\[ = 4\]