Question

The mercury content of sushi was sampled from 7 New York City grocery stores. The sample mean mercury content was x¯=0.719

x

¯

=

0.719

ppm and the sample standard deviation was s=0.366

s

=

0.366

ppm.

Construct a 90% confidence interval to estimate the mean mercury content of sushi from all NYC grocery stores.

Answer 1

We have given that,          
          
Sample mean =0.719 ppm  
Sample standard deviation =0.366 ppm
Sample size =7  
Level of significance=   1-0.90=0.1  
Degree of freedom =6  
          
t critical value is (by using t table)=   1.9432
          
Confidence interval formula is


=(0.450,0.988)          
          
          
          
Lower confidence limit=0.450  
          
Upper confidence limit=   0.988