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Chapter 7: Q. 55 (page 479)
Songs on an iPod Refer to Exercise 53 . How many songs would you need to sample if you wanted the standard deviation of the sampling distribution of to be 10 seconds? Justify your answer.
The sample should be 36 tracks if the sampling distribution's standard deviation is 10 seconds.
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A grocery chain runs a prize game by giving each customer a ticket that may win a prize when the box is scratched off. Printed on the ticket is a dollar value or the statement "This ticket is not a winner." Monetary prizes can be redeemed for groceries at the store. Here is the probability distribution of the amount won on a randomly selected ticket:
Which of the following are the mean and standard deviation, respectively, of the winnings?
a.
b.
c.
d.
e.
Healthy Living From a large group of people who signed a card saying they intended to quit smoking, people were selected at random. It turned out that of these individuals had not smoked over the past months.
Birth weights Researchers in Norway analyzed data on the birth weights of 400,000 newborns over a 6-year period. The distribution of birth weights is approximately Normal with a mean of 3668 grams and a standard deviation of 511 grams.
a. Sketch a graph that displays the distribution of birth weights for this population.
b. Sketch a possible graph of the distribution of birth weights for an SRS of size $5 . Calculate the range for this sample.
In this population, the range (Maximum - Minimum) of birth weights is 3417 grams. We technology to take 500 SRSs of size and calculate the range (Maximum Minimum) for each sample. The dotplot shows the results.
What does the CLT say? Asked what the central limit theorem says, a student replies, "As you take larger and larger samples from a population, the variability of the sampling distribution of the sample mean decreases." Is the student right? Explain your answer.
Social scientists are interested in the association between high school graduation rate (HSGR, measured as a percent) and the percent of U.S. families living in poverty (POV). Data were collected from all 50 states and the District of Columbia, and a regression analysis was conducted.
The resulting least-squares regression line is given by (HSGR) (HSGR) with . Based on the information, which of the following is the best interpretation for the slope of the least-squares regression line?
a. For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.896 .
b. For each 1 % increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.802.
c. For each 1 % increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.620.
d. For each 1 % increase in the percent of families living in poverty, the graduation rate is predicted to decrease by approximately 0.802.
e. For each 1 % increase in the percent of families living in poverty, the graduation rate is predicted to decrease by approximately 0.620.
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