1 A)A small amount of the trace element selenium, 50-200 micrograms (g) per day, is considered essential to good health. Suppose that random samples of

n₁=n₂= 50 adults

were selected from two regions of Canada and that a day's intake of selenium, from both liquids and solids, was recorded for each person. The mean and standard deviation of the selenium daily intakes for the 50 adults from region 1 were

x₁= 167.3

and

s₁= 24.6g,

respectively. The corresponding statistics for the 50 adults from region 2 were

x₂= 140.7

and

s₂= 17.5g.

Find a 95% confidence interval for the difference

(₁₂)

in the mean selenium intakes for the two regions. (Round your answers to three decimal places.)

----g to----g

B) Independent random samples were selected from populations 1 and 2. The sample sizes, means, and variances are as follows.

Population12Sample Size3549Sample Mean12.37.9Sample Variance1.384.14

(a) Find a 95% confidence interval for estimating the difference in the population means (₁₂). (Round your answers to two decimal places.)

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