Question

36. A study was conducted to see if music has an effect on productivity of workers. The music was turned on during the working hours of 32 randomly selected workers. The workers’ productivity level averaged 82 with a standard deviation of 25. On a different day the music was turned off and there were 50 randomly selected workers. Their productivity level averaged 58 with a standard deviation of 15. What is 90% confidence interval of the difference between the average productivity levels of these 2 groups of workers? : *
(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 the distribution of the age at which children begin to walk is estimated to be 1.5 months. A random sample of children will be selected, and the age at which each child begins to walk will be recorded. A 90 percent confidence interval for the average age at which children begin to walk will be constructed using the data obtained from the sample of children. Of the following, which is the smallest sample size that will result in a margin of error of 0.25 month or less for the confidence interval? : *
(A) 95
(B) 100
(C) 135
(D) 140
(E) 240

Answer 1

hence, correct option is (B) (16.66, 31.34).

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Hence, the correct option is A.