# STAT 230 Week 8 Quiz 2

March 26, 2017

STAT 230 Week 8 Quiz 2** in $15 Only**

1. A pollster selected 3 of 8 available people. How many different groups of 3 are possible?10%

2. Your firm has a contract to make 2000 staff uniforms for a fast –food retailer. The heights of the staff are normally distributed with a mean of 70 inches and a standard deviation of 3 inches. What percentage of uniforms will have to fit staff shorter than 67inches? What percentage will have to be suitable for staff taller than 76 inches.?

a) 16% & 2.5%

b) 68% & 95%

c) 32% & 5%

(15%)

3. The industry standards suggest that 10% of new vehicles require warranty service within the first year. A dealer sold 15 Nissans yesterday. Use equation for Binomial Probability for part a) and Table II for part b) & c). Show work!

a) What is the probability that none of these vehicles requires warranty service? Use the Binomial equation for P(X=0).

b) What is the probability that exactly one of these vehicles requires warranty service?

c) Determine the probability 2 or more of these vehicles require warranty service.

d) Compute the mean and std. dev. of this probability distribution.**(15%)**

4. Allen & Associates write weekend trip insurance at a very nominal charge. Records show that the probability a motorist will have an accident during the weekend and will file a claim I quite small (.0005). Suppose Alden wrote 400 policies for the forthcoming weekend. Compute the probability that exactly two claims will be filed using the equation

for Poisson Probability.

Note: The symbol λ is the mean (expected value) which we used as μ = np. So λ is nothing more than the mean number of occurrences (successes = np) in a particular interval.

Get the probability that the number of claims is 0, 1, 3 & 4 from Poisson Tables.

(10%)

5. Given a standard normal distribution, determine the following. Show Table Values

used in each part.

a) P(Z<1.4)

b) P(Z>1.4)

c) P(Z< -1.4)

d) P( – 0.50<Z<1.0)

e) P(0.50<Z<1.5)

15%

6. A company is considering offering child care for their employees. They wish to estimate the mean weekly child-care cost of their employees. A sample of 10 employees reveals the following amounts spent last week in dollars.

100 99 90 102 105 95 97 94 99 104

Develop a 90% confidence interval for the population mean. Interpret the result.

x =??, S=??, t / 2

=??, Range of = (??)

15%

7. The National Safety Council reported that 56 % of American turnpike drivers are men. A sample of 256 cars traveling southbound on the New Jersey Turnpike yesterday revealed that 165 were driven by men. At the .01 significance level, can we conclude that a larger proportion of men were driving on the New Jersey Turnpike

than the national statistics indicate? First, state H0 & Ha HO: ??, Ha: ??

a) Is this a Z or t test?

b) Test Statistic = ?

c) Critical value = ?

d) p-value = ?

e) Reject Ho: (yes or no)

15%

8. Given the hypothesis: H0: μ≥20 & Ha: μ<20, a random sample of five resulted in the following values: 18, 15, 12, 19, & 21. Using the .01 significance level, can we conclude the population mean is less than 20?

a) Is this a Z or t test?

b) Test statistic = ?

c) Critical value = ?

d) Reject Ho: (yes or no)

…..

**Price of Answer**: Just US$15 only

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