Statistics Question??

Question

I can't seem to figure this out.

A survey asks a random sample of 200 AP students from the Career Center if they think students should be required to attend study sessions for AP courses prior to the AP exams. 55% of Career Center students take AP courses. Let p(hat) denote the proportion in the sample that favor mandatory attendance. Suppose that 40% of all Career Center AP students favor mandatory attendance at study sessions.

The standard deviation is?

Answer 1

Binomial Variance = n * P(success) * P(failure)

so your Variance = 200 * 0.4 * 0.6 = 48

Since Variance = SD^2, SD = 6.93