A small amount of the trace element selenium, 50-200 micrograms (μg) per day, is considered essential to good health. Suppose that random samples of n1​=n2​=30 adults were selected from the two regions of the United States and that a day's intake of selenium was recorded for each person. The mean and standard deviation of the selenium daily intake for the 30 adults from region 1 were x1​=167.1 and s1​=24.3 μg, respectively. The corresponding statistics for the 30 adults from region 2 were x2​=140.9 and s2​=176 μg. Find a 95% confidence interval for the difference in the mean selenium intake for the two regions. Interpret this interval.