Question

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 (sysomos website, january 5, 2015). Suppose we randomly select 100 tweets.

Answer 1

Missing question is "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?"

a. The expected number of these tweets with no reaction is

Let x = Tweets with no reaction

E(x) = np

n= 100, p = 0.71

E(x) = (100)(0.71)

E(x) = 71

Hence, the expected number of these tweets with no reaction is 71.

b. б² = Product of n, p and (1-p)

б² = (100)(0.71)(0.29)

б² = 71*0.29

б² = 20.59

Hence, the variance for the number of these tweets with no reaction is 20.59

б =
`√(Product of n, p and (1-p))`

б =
`√( (100)(0.71)(0.29))`

б =
`√(71*0.29))`

б =
`√(20.59)`

б = 4.54

Hence, the standard deviation for the number of these tweets with no reaction is 4.54.