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

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 =

                                =

                              sd = 2.31862028

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x