What are the variance (to 2 decimals) and standard deviation (to 4 decimals) for the number of these tweets with no reaction?

The variance is 20.59; and the standard deviation is 4.5376.

Explanation:

First of all, there are 71% of tweets with no reaction in the study. Thus, the probability (p) is 0.71. Therefor, sample x follows binomial distribution

Secondly, if we randomly select 100 tweets, the sample size (n) will be 100.

The variance is

The standard deviation is the root-square of variance. Then, it is sqrt (20.59) = 4.5376