Download Circle the correct answer. Part 1 Problem 1 Which one is true? A) A

Circle the correct answer.
Part 1
Problem 1
Which one is true?
A) A sample of size n is selected at random from an infinite population. As n increases, the standard error of the
sample mean increases.
B) A sample of size 25 is selected from a population of size 500. The finite population correction is needed to
find the standard error of x
C) The mean of the sampling distribution of the sample proportion p when the sample size n=100 and the
population proportion P= 0.92, is 92.0.
D) Given a mean of 2.1 and a standard deviation of 0.7, a 90% confidence interval will be 2.1 ± 0.7.
E) A regression analysis between sales (in $1000) and advertising (in $100) resulted in the following least
squares line: y = 77 + 8x. This implies that if advertising is $600, then the predicted amount of sales (in
dollars) is $125,000.
Problem 2
Which statements are false?
A) If the coefficient of correlation is —0.81, then the percentage of the variation in y that is explained by the
regression line is 81%.
B) In an effort to identify the true proportion of college freshman who are under 18 years of age, a random sample
of 500 freshmen was taken. Fifty of them were under the age of 18. The value 0.10 is a point estimate of the true
proportion of freshman under age 18.
C) The lower limit of the 90% confidence interval for  where n = 64, x = 70, and  = 20, is 65.89.
D) A one -tail test for the population mean  produces a test -statistic z= -0.75. The p -value associated with the test
is 0.7734.
E,) As a general rule, the normal distribution is used to approximate the sampling distribution of the sample
proportion only if the sample size n is greater than or equal to 30.
Problem 3
A) The sample variance s2 is an unbiased estimator of the population variance o2 when the
denominator of s2 is n.
B) Suppose a sample size of 5 has mean 9.60. If the population variance is 5 and the population
is normally distributed, the lower limit for a 92% confidence interval is 7.85.
C)To estimate with 95% confidence the mean of a normal population whose standard deviation is assumed
to be 4 and the maximum allowable sampling error is assumed to be 1, requires a random sample of size 62.
D) If the coefficient of determination is 1.0, then the coefficient of correlation must be 1.0
E) If the coefficient of determination is 0.95, this means that 95% of the variation in the independent
variable x can be explained by the y variable.
The following data show the brand, price ($).and the overall score for six headphones that were tested by
Consumer Reports
Brand
Price
Score
Bose
Skull candy
Koss
Phillips
Denon
JVC
180
150
95
70
70
35
76
71
61
56
40
26
4) Write the Estimated regression equation
5) Interpret the coefficients of the equation
6) Predict the score of the headphone when price is S 100.
7) Find the coefficient of determination. Explain what it means
8) Find the coefficient of correlation. Explain what it means
The amount of time spent by American adults playing sports per week is normally distributed
with a mean of 4 hours and standard deviation of 1.25 hours.
9) Find the probability that a randomly selected American adult plays sports for more than 5
hours per week
10) Find the probability that if 4 American adults are randomly selected, their average number of
hours spent playing sports is more than 5 hours per week.
A random sample of 10 college students was drawn from a large university. Their ages are
22,17, 27, 20,23, 19, 24, 18, 19, and 24 years.
110Estimate the population mean with 90% confidence.
Researcher at the University of Michigan medical school believes that coffee
consumption may increase heart rate. Suppose it is known that heart rate (in beats
per minute) is normally distributed with an average of 70 bpm for adults. A
random sample of 25 adults was selected and was found that their average
heartbeat was 73 bpm after coffee consumption, with a standard deviation of 7
bpm.
12)Formulate the null and alternative hypotheses.
13) Test the hypotheses at the 10% significance level to determine if we can infer that coffee
consumption increases heart rate.