Question 6

 

Consider the following results for two samples randomly taken from two normal populations with equal variances.

		Sample I	Sample II
	Sample Size	28	35
	Sample Mean	48	44
	Population Standard Deviation	9	10

a.   Develop a 95% confidence interval for the difference between the two population means.

b.   Is there conclusive evidence that one population has a larger mean? Explain.

 

Question 13

 

A small stock brokerage firm wants to determine the average daily sales (in dollars) of stocks to their clients. A sample of the sales for 36 days revealed average daily sales of $200,000. Assume that the standard deviation of the population is known to be $18,000.

a.  Provide a 90% confidence interval estimate for the average daily sale.

b.  Provide a 99% confidence interval estimate for the average daily sale.

uestion 21

 

The weight of a .5 cubic yard bag of landscape mulch is uniformly distributed over the interval from 38.5 to 41.5 pounds.

What is the probability that a bag will weigh less than 41 pounds?

 

Question 24

 

The weekly earnings of fast-food restaurant employees are normally distributed with a mean of $395. If only 10.2% of the employees have a weekly income of more than $422.94, what is the value of the standard deviation of the weekly earnings of the employees?

 

Question 25

 

An investment advisor recommends the purchase of shares in Infogenics, Inc.  He has made the following predictions:

P(Stock goes up 20% | Rise in GDP) = .6

P(Stock goes up 20% | Level GDP)    = .5

P(Stock goes up 20% | Fall in GDP)    = .4

An economist has predicted that the probability of a rise in the GDP is 20%, whereas the probability of a fall in the GDP is 40%.

What is the probability that the stock will go up 20%?

 

Question 27

 

An investment advisor recommends the purchase of shares in Infogenics, Inc.  He has made the following predictions:

P(Stock goes up 20% | Rise in GDP) = .6

P(Stock goes up 20% | Level GDP)    = .5

P(Stock goes up 20% | Fall in GDP)    = .4

An economist has predicted that the probability of a rise in the GDP is 20%, whereas the probability of a fall in the GDP is 40%.

We have been informed that the stock has gone up 20%.  What is the probability of a rise or fall in the GDP?