Construct a 95% confidence interval for the population mean time spent waiting.
You are testing that the mean speed of your cable Internet connection is more than three Megabits per
second. State the null and alternative hypotheses. What is the Ho and H1
Q2
A sociologist claims the probability that a person picked at random in Times Square in New York City is
visiting the area is 0.83. You want to test to see if the claim is correct. State the null and alternative
hypotheses. What is the Ho and H1
Q3
A hospital is trying to cut down on emergency room wait times. It is interested in the amount of time
patients must wait before being called back to be examined. An investigation committee randomly
surveyed 70 patients. The sample mean was 1.5 hours with a sample standard deviation of 0.5 hours.
Identify the following:
a. x = ____
b. sx = ____
c. n = ____
d. n – 1 = ____
Q4
A hospital is trying to cut down on emergency room wait times. It is interested in the amount of time
patients must wait before being called back to be examined. An investigation committee randomly
surveyed 70 patients. The sample mean was 1.5 hours with a sample standard deviation of 0.5 hours.
Construct a 95% confidence interval for the population mean time spent waiting.
Ans: CI: (1.3808 and 1.6192) Show your workings
Q5
One hundred eight Americans were surveyed to determine the number of hours they spend watching
television each month. It was revealed that they watched an average of 151 hours each month with a
standard deviation of 32 hours. Assume that the underlying population distribution is normal.
Find the 99% confidence interval for the population mean hours spent watching television per month.
Ans; CI: (142.92 and 159.08) Show your workings
Q6
The systolic blood pressure (given in millimeters) of males has an approximately normal distribution with
mean μ = 125 and standard deviation σ = 14. Systolic blood pressure for males follows a normal
distribution. Calculate the z-scores for the male systolic blood pressures 100 and 150 millimeters.
Ans: Z = -1.8 and 1.8
Q7
A baker is deciding how many batches of muffins to make to sell in his bakery. He wants to make enough to
sell everyone and no less. Through observation, the baker has established a probability distribution.
x P(x)
1 0.15
2 0.35
3 0.40
4 0.10
What is the probability the baker will sell more than one batch? P (x > 1)
Ans: 0.85 (Show your workings)
Q8
A candy bar manufacturer is interested in trying to estimate how sales are influenced by the price of their
product. To do this, the company randomly chooses 6 small cities and offers the candy bar at different prices.
Using candy bar sales as the dependent variable, the company will conduct a simple linear regression on the
data below:
City Price ($) Sales
River City 1.30 100
Hudson 1.60 90
Ellsworth 1.80 90
Prescott 2.00 40
Rock Elm 2.40 38
Stillwater 2.90 32
what is the coefficient of correlation for these data? Ans= -0.8854 (Show detailed workings)
Q9
Suppose that history shows that 60% of college students prefer Brand C cola. A sample of 5 students is to be
selected.
(a) Find the mean of this binomial distribution (Ans=3) (Show your solution)
(b) Find the variance of the binomial distribution (Ans=1.2) (Show your solution)
Q10
A manufacturer of power tools claims that the mean amount of time required to assemble their top-of-the-line
table saw is 80 minutes with a standard deviation of 40 minutes. Suppose a random sample of 64 purchasers of
this table saw is taken. The probability that the sample mean will be greater than 88 minutes is ________.
Answer: 0.0548 (Show your solution)
