20-4 x(-6)= steps to solve
1 answer:
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Complete Question
According to a study conducted by the Toronto-based social media analytics firm Sysomos, 75% of all tweets get no reaction. That is, these are tweets that are not replied to or retweeted (Sysomos website, January ). Suppose we randomly select tweets.
a. What is the expected number of these tweets with no reaction (to the nearest whole number)?
b. What are the variance (to 2 decimals) and standard deviation (to 4 decimals) for the number of these tweets with no reaction? Variance Standard deviation
Answer:
a
The mean is
The variance
The standard deviation is
Step-by-step explanation:
A binomial distribution is mathematically represented as
where n denotes the number of independent trials =200
And p denote the probability of success = 0.75
We also have the probability of failure which is denoted as q and is equivalent to
if p and q are constant then
In binomial distribution the probability of x success and (n-x) is mathematically represented as
Where x= 0,1,2,...,n
Now
Now the mean(Expected number ) of these probability in binomial distribution is mathematically represented as
And the variance is mathematically represented as
And the standard deviation is mathematically represented as
We can obtain the standard z -score of a d