Cumulative Exam — Unit test Answers

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21
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A simple random sample of size n is drawn from a normally distributed population, and the mean of the sample is , while the standard deviation is s. What is the 99% confidence interval for the population mean? Use the table below to help you answer the question.Confidence Level90%95%99%z*-score1.6451.962.58

Question illustration
A
x Overbar plus-or-minus StartFraction 0.90 times s Over StartRoot n EndRoot EndFraction
Option A
B
x Overbar plus-or-minus StartFraction 0.99 times s Over StartRoot n EndRoot EndFraction
Option B
C
x Overbar plus-or-minus StartFraction 1.645 times s Over StartRoot n EndRoot EndFraction
Option C
D
x Overbar plus-or-minus StartFraction 2.58 times s Over StartRoot n EndRoot EndFraction
Option D
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The mean of a set of credit scores is and . Which statement must be true about z694?

Question illustration
A
z694 is within 1 standard deviation of the mean.
B
z694 is between 1 and 2 standard deviations of the mean.
C
z694 is between 2 and 3 standard deviations of the mean.
D
z694 is more than 3 standard deviations of the mean.
23

The resting heart rates for 80 women aged 46–55 in a simple random sample are normally distributed, with a mean of 71 beats per minute and a standard deviation of 6 beats per minute. Assuming a 90% confidence level (90% confidence level = z-score of 1.645), what is the margin of error for the population mean?Remember, the margin of error, ME, can be determined using the formula .

Question illustration
A
0.66
B
1.10
C
1.31
D
1.73
24

According to a poll, 56% of voters support funding a new community center. A surveyor randomly selects 75 voters and asks each voter if he or she is in favor of the center. If being in favor of the center is a success, what is the probability of a success for this binomial experiment?

A
0.34
B
0.44
C
0.56
D
0.75
25

Dwayne and Alisha both correctly graphed a standard normal curve. Which of the following statements is true?

A
Neither the means nor the standard deviations of Dwayne’s and Alisha’s graphs must be the same.
B
The means of Dwayne’s and Alisha’s graphs must be the same but not the standard deviations.
C
The standard deviations of Dwayne’s and Alisha’s graphs must be the same but not the means.
D
Both the means and the standard deviations of Dwayne’s and Alisha’s graphs must be the same.

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