Answer:
Mean = 3.4
Variance = 1.088
Standard deviation = 1.0431
Step-by-step explanation:

The mean of a binomial distribution with parameters N (the number of trials) and p (the probability of success for each trial) is 
Thus,

The variance of the binomial distribution is
, where
is the variance of the binomial distribution, so

The standard deviation
is the square root of the variance
so

Answer:
D
Step-by-step explanation:

To solve this one-step equation you:
1. Substract 9 in both sides of the equation:
In this step is the mistake as Sara gets as result -4x=29 and the corret result of substract 9 in both sides of the equation is 5x=20.
2. Divide both sides of the equation into 5:
Then, the answer that Sara should found for the equation is x=4