Calculate the standard deviation of the given random variable X. Please round your answer to two decimal places.
Forty-five darts are thrown at a dartboard. The probability of hitting a bull's-eye is 0.4. Let X be the number of bull's-eyes hit.

A) $\sigma = 10.8$
B) $\sigma = 18$
C) $\sigma = 4.24$
D) $\sigma = 3.29$
E) $\sigma = 5.4$

Question

Calculate the standard deviation of the given random variable X. Please round your answer to two decimal places.  
Forty-five darts are thrown at a dartboard. The probability of hitting a bull's-eye is 0.4. Let X be the number of bull's-eyes hit.
 
A) $\sigma = 10.8$
B) $\sigma = 18$
C) $\sigma = 4.24$
D) $\sigma = 3.29$
E) $\sigma = 5.4$

Quizplus · Accepted Answer

The standard deviation for a binomial distribution is calculated using the formula $\sigma = \sqrt{n \cdot p \cdot (1-p)}$. Here, $n = 45$ and $p = 0.4$, so $\sigma = \sqrt{45 \cdot 0.4 \cdot 0.6} = 3.29$.

Calculate the Standard Deviation of the Given Random Variable X σ=10.8\sigma = 10.8σ=10.8

Calculate the Standard Deviation of the Given Random Variable X $\sigma = 10.8$