Devry MATH221 Week 5 Quiz Latest 2021 June

MATH221 Statistics for Decision Making

Week 5 Quiz

Question 1(CO 4) From a random sample of 55 businesses, it is found that the mean time that employees spend on personal issues each week is 4.9 hours with a standard deviation of 0.35 hours. What is the 95% confidence interval for the amount of time spent on personal issues?

  (4.82, 4.98)

  (4.83, 4.97)

  (4.84, 4.96)

  (4.81, 4.99)

 Question 2(CO 4) If a confidence interval is given from 8.56 to 10.19 and the mean is known to be 9.375, what is the maximum error?

  0.408

  1.630

  0.815

  8.560 

Question 3(CO 4) Which of the following is most likely to lead to a large margin of error?

  small sample size

  large sample size

  small standard deviation

  small mean

 Question 4(CO 4) From a random sample of 85 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?

  (25.89, 37.71)

  (30.75, 32.85)

  (30.62, 32.99)

  (19.98, 43.62)

 Question 5(CO 4) A company making refrigerators strives for the internal temperature to have a mean of 37.5 degrees with a 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?

  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)

  No, the temperature is outside the confidence interval of (37.40, 37.60)

  Yes, the temperature is within the confidence interval of (37.40, 37.60)

 Question 6(CO 4) What is the 97% confidence interval for a sample of 104 soda cans that have a mean amount of 12.05 ounces and a population standard deviation of 0.08 ounces?

  (12.035, 12.065)

  (11.970, 12.130)

  (12.033, 12.067)

  (11.998, 12.102)

 Question 7(CO 4) Determine the minimum sample size required when you want to be 98% confident that the sample mean is within two units of the population mean. Assume a standard deviation of 4.82 in a normally distributed population.

  32

  31

  34

  33

 Question 8(CO 4) Determine the minimum sample size required when you want to be 80% confident that the sample mean is within 1.3 units of the population mean. Assume a standard deviation of 9.24 in a normally distributed population.

  195

  84

  194

  83

 Question 9(CO 4) Determine the minimum sample size required when you want to be 75% confident that the sample mean is within twenty units of the population mean. Assume a standard deviation of 327.8 in a normally distributed population

  557

  1422

  727

  356

 Question 10(CO 4) In a sample of 8 high school students, they spent an average of 24.8 hours each week doing sports with a standard deviation of 3.2 hours. Find the 95% confidence interval.

  (21.60, 28.00)

  (22.66, 26.94)

  (22.12, 27.48)

  (24.10, 25.50)

 Question 11 (CO 4) In a sample of 15 stuffed animals, you find that they weigh an average of 8.56 ounces with a standard deviation of 0.08 ounces. Find the 92% confidence interval.

  (8.516, 8.604)

  (8.543, 8.577)

  (8.528, 8.591)

  (8.521, 8.599)

 Question 12(CO 4) Market research indicates that a new product has the potential to make the company an additional $3.8 million, with a standard deviation of $1.8 million. If this estimate was based on a sample of 10 customers, what would be the 90% confidence interval?

  (2.51, 5.09)

  (2.00, 5.60)

  (3.06, 4.54)

  (2.76, 4.84)

 Question 13(CO 4) Supplier claims that they are 95% confident that their products will be in the interval of 20.45 to 21.05. You take samples and find that the 95% confidence interval of what they are sending is 20.32 to 21.48. What conclusion can be made?

  The supplier products have a lower mean than claimed

  The supplier is more accurate than they claimed

  The supplier is less accurate than they have claimed

  The supplier products have a higher mean than claimed

 Question 14(CO 4) In a sample of 15 small candles, the weight is found to be 3.72 ounces with a standard deviation of 0.963 ounces. What would be the 87% confidence interval for the size of the candles?

  (1.794, 5.646)

  (3.369, 4.071)

  (2.757, 4.683)

  (3.320, 4.120)

 Question 15(CO 4) In a situation where the standard deviation was increased from 3.1 to 5.8, what would be the impact on the confidence interval?

  It would become narrower due to the increased standard deviation

  It would become wider due to the increased standard deviation

  It would become narrower with more values

  It would remain the same as standard deviation does not impact confidence intervals

 Question 16(CO 4) In a random sample of fourteen people, the mean time at lunch was 28.4 minutes with a standard deviation of 8.2 minutes.  Assuming the data are normally distributed, what would be the 85% confidence interval?

  (35.25, 41.55)

  (25.44, 31.36)

  (35.05, 41.75)

  (25.05, 31.75)

 Question 17(CO 4) If a confidence interval is known to be (56.28, 62.72), what would be its margin of error?

  6.78

  3.22

  6.44

  1.61

 Question 18(CO 4) A company manufacturers soda cans with a diameter of 52 millimeters.  In a sample of 7 cans, the standard deviation was 2.3 millimeters.  What would be the 96% confidence interval for these cans?

  (49.87, 54.13)

  (49.73, 54.27)

  (50.86, 53.14)

  (49.95, 54.05)