MATH 221 Week 5 Quiz 2

MATH 221 Week 5 Quiz 2 | Devry University

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 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?  

·         (5.71, 5.89)  

·         (5.73, 5.87)  

·         (5.74, 5.90)  

·         (5.72, 5.88)

 Question 2

 (CO 4) If a confidence interval is given from 8.52 to 10.23 and the mean is known to be 9.375, what is the maximum error?  

·         1.710  

·         8.520  

·         0.428  

·         0.855

 Question 3

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

·         large sample size  

·         large maximum error  

·         small mean  

·         small standard deviation

 Question 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 3.65 hours. What is the 90% confidence interval for the amount of time they spend online each week?  

·         (30.86, 32.74)  

·         (28.15, 35.45)  

·         (29.99, 33.61)  

·         (24.50, 39.10)

 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?  

·         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 (36.90, 38.10)   

·         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?  

·         (12.033, 12.067)  

·         (12.035, 12.065)  

·         (11.970, 12.130)  

·         (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.  

·         33  

·         31  

·         34    

·         32

 Question 8

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

·         141  

·         195  

·         36  

·         231

Question 9

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

·         632  

·         1835  

·         1293  

·         785

 Question 10

 (CO 4) In a sample of 8 high school students, they spent an average of 25.8 hours each week doing sports with a standard deviation of 3.2 hours. Find the 95% confidence interval.  

·         (19.40, 32.20)  

·         (23.12, 28.48)  

·         (22.60, 29.00)  

·         (23.15, 28.50)

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 0.06 ounces. Find the 92% confidence interval.  

·         (8.527, 8.593)  

·         (8.521, 8.599)    

·         (8.531, 8.589)  

·         (8.526, 8.594)

 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 $1.9 million. If this estimate was based on a sample of 10 customers, what would be the 90% confidence interval?  

·         (2.70, 4.90)  

·         (2.51, 5.09)  

·         (2.00, 5.60)  

·         (1.90, 5.71)

 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 is more accurate than they claimed  

·         The supplier products have a higher mean than claimed  

·         The supplier products have a lower mean than claimed   

·         The supplier is less accurate than they have claimed

 Question 14

 (CO 4) In a sample of 19 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?  

·         (3.369, 4.071)  

·         (3.337, 4.103)  

·         (3.371, 4.069)  

·         (3.199, 4.241)

 Question 15

 (CO 4) In a situation where the sample size was increased from 29 to 39, what would be the impact on the confidence interval?  

·         It would remain the same as sample size does not impact confidence intervals  

·         It would become wider due to using the t distribution   

·         It would become narrower with more values    

·         It would become narrower with fewer values

 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?  

·         (25.05, 31.75)  

·         (25.44, 31.36)  

·         (35.25, 41.55) 

·         (35.05, 41.75)

Question 17

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

·         3.22  

·         6.78  

·         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?  

·         (49.95, 54.05)    

·         (49.73, 54.27)  

·         (49.87, 54.13)  

·         (50.86, 53.14)