Solution
We know that the mean= 3.72$ and the sd= 0.10$
and using the Chebysev theorem we want to know whick percentage of stores will be between 3.42$ and $4.02
We can calculate the distance between the limits and the mean:
3.72 - 3.42= 0.3
k=0.3/0.1= 3
4.02-3.72= 0.3
k= 0.3/0.1 = 3
Then we are between 3 deviations from the mean
So then we can calculate the percentage required with this formula:
So then we expect at least 88.9%