Question

The 2011 gross sales of all firms in a large city have a mean $2.5 million and a standard deviation of $0.6 million. Using chebyshev theorem, find at least what percentage of firm city 2011 gross sales of $1.3 to $3.7 million

Answer 1

The mean :  2.5 million
S D = 0.6 million
2.5 - 2 · 0.6 = 2.5 - 1.2 = 1.3 million
2.5 + 2 · 0.6 = 2.5 + 1.2 = 3.7 million
Chebyshev theorem : at least 3/4 of the data lie within 2 standard deviations of the mean.
Answer:
At least 75 % of all firms.