MATH 221 Week 7 Quiz (2): Statistics for
Decision-Making
1. (CO 4) From a random sample of 68 businesses, it is found that the mean time that employees
spend on personal issues each week is 5.8 hours with a standard deviation of 0.35 hours. What
is the 95% confidence interval for the amount of time spent on personal issues?
(5.74, 5.90)
(5.73, 5.87)
(5.71, 5.89)
(5.72, 5.88)
2. (CO 4)If a confidence interval is given from 8.50 to 10.25 and the mean is known to be 9.375,
what is the margin of error?
8.500
0.875
0.438
1.750
, 3. (CO 4) If the population standard deviation of a sample increases without other changes, what is
most likely to happen to the confidence interval?
does not change
narrows
widens
cannot determine
4. (CO 4) From a random sample of 41 teens, it is found that on average they spend 31.8 hours
each week online with a population standard deviation of 5.91 hours. What is the 90%
confidence interval for the amount of time they spend online each week?
(30.62, 32.99)
(29.99, 33.61)
(30.28, 33.32)
(25.89, 37.71)
5. (CO 4) A company making refrigerators strives for the internal temperature to have a mean of
37.5 degrees with a population standard deviation of 0.6 degrees, based on samples of 100. A
sample of 100 refrigerators have an average temperature of 37.53 degrees. Are the refrigerators
within the 90% confidence interval?
No, the temperature is outside the confidence interval of (37.40, 37.60)
Yes, the temperature is within the confidence interval of (36.90, 38.10)
No, the temperature is outside the confidence interval of (36.90, 38.10)
Yes, the temperature is within the confidence interval of (37.40, 37.60)
6. (CO 4) What is the 97% confidence interval for a sample of 104 soda cans that have a mean
amount of 12.10 ounces and a population standard deviation of 0.08 ounces?
(12.033, 12.067)
(12.083, 12.117)
(12.035, 12.065)
(12.020, 12.180)
Decision-Making
1. (CO 4) From a random sample of 68 businesses, it is found that the mean time that employees
spend on personal issues each week is 5.8 hours with a standard deviation of 0.35 hours. What
is the 95% confidence interval for the amount of time spent on personal issues?
(5.74, 5.90)
(5.73, 5.87)
(5.71, 5.89)
(5.72, 5.88)
2. (CO 4)If a confidence interval is given from 8.50 to 10.25 and the mean is known to be 9.375,
what is the margin of error?
8.500
0.875
0.438
1.750
, 3. (CO 4) If the population standard deviation of a sample increases without other changes, what is
most likely to happen to the confidence interval?
does not change
narrows
widens
cannot determine
4. (CO 4) From a random sample of 41 teens, it is found that on average they spend 31.8 hours
each week online with a population standard deviation of 5.91 hours. What is the 90%
confidence interval for the amount of time they spend online each week?
(30.62, 32.99)
(29.99, 33.61)
(30.28, 33.32)
(25.89, 37.71)
5. (CO 4) A company making refrigerators strives for the internal temperature to have a mean of
37.5 degrees with a population standard deviation of 0.6 degrees, based on samples of 100. A
sample of 100 refrigerators have an average temperature of 37.53 degrees. Are the refrigerators
within the 90% confidence interval?
No, the temperature is outside the confidence interval of (37.40, 37.60)
Yes, the temperature is within the confidence interval of (36.90, 38.10)
No, the temperature is outside the confidence interval of (36.90, 38.10)
Yes, the temperature is within the confidence interval of (37.40, 37.60)
6. (CO 4) What is the 97% confidence interval for a sample of 104 soda cans that have a mean
amount of 12.10 ounces and a population standard deviation of 0.08 ounces?
(12.033, 12.067)
(12.083, 12.117)
(12.035, 12.065)
(12.020, 12.180)
