Question

You operate an auto store that sells tires. You are concerned about warranty returns on the tires. Company records show that the probability warranty repair for a tire in the first 90 day is .05. You are tracking the sales of three tires. What is the mean for this binomial distribution?

a. .15

b. .19

c .25

d. .35

ABC Trucking Company realized that on an annual basis the distance traveled is normally distributed with a mean of 50,000 miles and a standard deviation of 12,000 miles. How many miles will be traveled by at least 80% of the trucks? (Hint: Think about the left side of the normal curve!)

a. 39,920

b. 43,500

c. 41,000

d. 38,670

Answer 1

Solution :

1) Given that,

p = 0.05

n = 3

Using binomial distribution,

Mean = = n * p = 3 * 0.05 = 0.15

correct option is = a

2) Given that,

mean = = 50000

standard deviation = = 12000

Using standard normal table,

P(Z > z) = 80%

= 1 - P(Z < z) = 0.80

= P(Z < z) = 1 - 0.80

= P(Z < z ) = 0.20

= P(Z < -0.84 ) = 0.20

z = -0.84

Using z-score formula,

x = z * +

x = -0.84 * 12000 + 50000

x = 39920

correct option is = a