It a recent study of college students indicated that 30% of all college students had at least one tattoo. A small private college decided to randomly and independently sample 15 of their students
And ask if they have a tattoo. Find the standard deviation for this binomial random variable.
Round to the nearest hundredth when necessary.
A)4.5
B)3.15
C)10.5
D)1.77

Question

Quizplus · Accepted Answer

The standard deviation for a binomial random variable is given by the formula $\sqrt{n \cdot p \cdot (1-p)}$, where $n$ is the number of trials (in this case, 15 students), and $p$ is the probability of success (in this case, 0.30 for having at least one tattoo). Plugging in the values, we get $\sqrt{15 \cdot 0.30 \cdot (1-0.30)} = \sqrt{15 \cdot 0.30 \cdot 0.70} = \sqrt{3.15} \approx 1.77$.

It a Recent Study of College Students Indicated That 30