Canadians are becoming more conscious of the importance of good nutrition, and some researchers believe that we may be altering our diets to include less red meat and more fruits and vegetables. To test this theory, a researcher decides to select hospital nutritional records for subjects surveyed 10 years ago and to compare the average amount of beef consumed per year to the amounts consumed by an equal number of subjects she will interview this year. She knows that the amount of beef consumed annually by Canadians ranges from 0 to approximately49kg. How many subjects should the researcher select for each group if she wishes to estimate the difference in the average annual per-capita beef consumption correct to within2.2kg with 99% confidence? (Round your answer up to the nearest whole number.) _________________subjects

2. 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=20adults 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 the20adults fromregion 1were x₁=167.5 and s₁=23.5g, respectively. The corresponding statistics for the20adultsfromregion 2were

x₂=140.1 and s₂=17.3g.

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

3. Independent random samples of size 80 are drawn from two quantitative populations, producing the sample information in the table.

	Sample 1	Sample 2
Sample Size	80	80
Sample Mean	15	8
Sample Standard Deviation	5	8

Find a 95% upper confidence bound for the difference in the two population means

(_{1 2}). (Round your answer to two decimal places.) _________________