Question

A food safety guideline is that the mercury in fish should be below 1 part per million​ (ppm). Listed below are the amounts of mercury​ (ppm) found in tuna sushi sampled at different stores in a major city. Construct a 99​% confidence interval estimate of the mean amount of mercury in the population. Does it appear that there is too much mercury in tuna​ sushi?

Mercury (ppm)
0.53
0.69
0.11
0.93
1.24
0.53
0.89

Answer 1

solution:-

given that

from the values

mean = 0.7029 , standard deviation = 0.3621

n = 7

degree of freedom df = n-1 = 7 - 1 = 6

we look into t table with df and probability of (1-0.99) is 0.01

critical value t = 3.707

confidence interval formula

=> mean +/- t * standard deviation/sqrt(n)

=> 0.7029 +/- 3.707 * 0.3621/sqrt(7)

=> 0.196 < μ < 1.210

Does it appear that there is too much mercury in tuna​ sushi?

=> Yes, because it is possible that the mean is greater than 1 ppm .Also at least one of the sample values exceeds 1 ppm , so at least some of the fish have too much mercury