Find mu sigma and unusual values 1 Random guesses are made f

Find mu, sigma, and unusual values.

1. Random guesses are made for the 60 multiple choice questions on the math portion of the ACT test. (n=60, p=1/5)

2. Mars Inc claims that 20% of its candies are orange, and a sample of 100 such candies is randomly selected. Find the mean and std dev for the num of orange candies.

3. 370 adults who regret getting tattoos, 20% say that they were too young at the time of getting tattoos. For randomly selected group of 370, find mean and std dev for the number who say that they were too young at that time.

Solution

Find mu, sigma, and unusual values.

n=60

P=1/5= 0.2

Expectation = np = 12

Variance = np(1 - p) = 9.6

Standard deviation = 3.0984

Unusual values= ( mean-2*sd, mean+2*sd) =(3.4032, 15.7968)

n=100

P=0.2

Expectation = np = 20

Variance = np(1 - p) = 16

Standard deviation = 4

Unusual values= ( mean-2*sd, mean+2*sd) =( 8, 24)

n=370

P=0.2

Expectation = np = 74

Variance = np(1 - p) = 59.2

Standard deviation = 7.6942

Unusual values= ( mean-2*sd, mean+2*sd) =(58.6116, 89.3884)