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.

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 =

б =

б =

б =

б = 4.54

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

the first successful, urban blues recording, selling more than 75,000 copies, was made in year 1920.

mamie smith recorded the first commercially successful example of the urban blues,   with the recording of “crazy blues”."crazy blues" was recorded on august 10, 1920, in new york city. within a month of the release of “crazy blues” it had sold 75,000 copies.

hi : ) i found this so i hope this !

"we first find value of tax in dollars.

the difference between the two prices   is: 23. 54 - 22 = 1.54

therefore the sales tax in dollars is 1.54

the tax % will be   (amount of tax / original cost price ) × 100

(1.54 / 22) × 100  → (0.07) × 100 =   7

so the tax rate is 7%

we can double check the answer.

7 % of 22   → (7/100) × 22 → 0.07 × 22 = 1.54

22 + 1.54 = 23.54"