The 2011 gross sales of all firms in a large city have a mean of $2.5

The 2011 gross sales of all firms in a large city have a mean of $2.5

The 2011 gross sales of all firms in a large city have a mean of $2.5 million and a standard deviation of $ 0.6 million. Using Chebyshev’s theorem, find at least what percentage of firms in this city had 2011 gross sales of $1.4 to $3.6 million.