36. A study was conducted to see if music has an effect onproductivity of workers. The music was turned on during the workinghours of 32 randomly selected workers. The workers’ productivitylevel averaged 82 with a standard deviation of 25. On a differentday the music was turned off and there were 50 randomly selectedworkers. Their productivity level averaged 58 with a standarddeviation of 15. What is 90% confidence interval of the differencebetween the average productivity levels of these 2 groups ofworkers? : *
(A) (15.94, 32.06)
(B) (16.66, 31.34)
(C) (16.74, 31.26)
(D) Unable to determine because assumptions are not met.
37. Based on previous research, the standard deviation of thedistribution of the age at which children begin to walk isestimated to be 1.5 months. A random sample of children will beselected, and the age at which each child begins to walk will berecorded. A 90 percent confidence interval for the average age atwhich children begin to walk will be constructed using the dataobtained from the sample of children. Of the following, which isthe smallest sample size that will result in a margin of error of0.25 month or less for the confidence interval? : *
(A) 95
(B) 100
(C) 135
(D) 140
(E) 240
