Question

The probability that an individual is left-handed is 0.16. In a class of 40 students, what is the mean (or expected value) and standard deviation of the number of left-handers in the class?
A. mean: 40; standard deviation: 2.52982213
B. mean: 6.4; standard deviation: 2.52982213
C. mean: 6.4; standard deviation: 2.31862028
D. mean: 40; standard deviation: 2.31862028

Answer 1

Answer:

C. mean: 6.4 and standard deviation: 2.31862028

Step-by-step explanation:

We are given

n=40

p=0.16

q= 1-p = 0.84

mean = np = 40*0.16 = 6.4

standard deviation =$\sqrt{ np(1-p) }$

                                = $\sqrt{40*.016*(1- 0.16)}$

                              sd = 2.31862028