According to a 2010 study conducted by the Toronto-based social media analytics firm Sysomos, 71% of all tweets get no reaction. That is, these are tweets that are not replied to or retweeted.Suppose we randomly select400tweets.

(a)

What is the expected number of these tweets with no reaction?

(b)

What are the variance and standard deviation for the number of these tweets with no reaction? (Round your answer for the standard deviation to four decimal places.)