If x is a binomial random variable with n=10 and p=0.8, the standard deviation of x is _________.
A)8.0
B)1.26
C)1.60
D)64.0
E)10

Question

Quizplus · Accepted Answer

The standard deviation of a binomial random variable is given by the formula $\sqrt{n \cdot p \cdot (1-p)}$. Substituting $n=10$ and $p=0.8$ gives $\sqrt{10 \cdot 0.8 \cdot (1-0.8)} = \sqrt{10 \cdot 0.8 \cdot 0.2} = \sqrt{1.6} \approx 1.26$.

If X Is a Binomial Random Variable with N=10 and P=0.8