Listed below are the amounts of mercury in parts per million

Listed below are the amounts of mercury (in parts per million, or ppm) found in tuna sushi sampled at different stores. The sample mean is 1.160 ppm and the sample standard deviation is 0.313 ppm. Use technology to construct a 90% confidence interval estimate of the mean amount of mercury in the population.

1.49 0.92 1.28 1.37 1.45 0.92 0.69

What is the confidence interval estimate of the mean amount of mercury in the population?

___ ppm < < ___ppm

(Round to three decimal places)

Solution

Confidence Interval
CI = x ± t a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Confidence Level/100)
ta/2 = t-table value
CI = Confidence Interval
Mean(x)=1.16
Standard deviation( sd )=0.313
Sample Size(n)=7
Confidence Interval = [ 1.16 ± t a/2 ( 0.313/ Sqrt ( 7) ) ]
= [ 1.16 - 1.943 * (0.118) , 1.16 + 1.943 * (0.118) ]
= [ 0.93,1.39]

=0.93 ppm < < 1.39ppm