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

Question

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 0.881 ppm and the sample standard deviation is 0.156 ppm. Use technology to construct a 90% confidence interval estimate of the mean amount of mercury in the population.

0.72

0.84

0.88

0.83

0.72

1.06

1.12

 

Answer 1

I used MS Excel per the instructions.

90% confidence ---> 1.645

 

 mean +or- 1.645*stddev/sqrt(n)

 

Mean is 0.881429

stddev is 0.155609

N=7

 

The lower limit (using the negative branch): 0.784678

The upper limit (using the positive branch): 0.978179