The mean length of the first 20 space shuttle flights was about 7 days with a standard deviation of about 2 days. Using Chebychev's theorem, at least how many of the flights lasted between 3 and 11 days.

Answer 1

n = 20
µ = 7
σ = 2

(7-2(2), 7+ 2(2)

(µ-2σ, µ + 2σ)

k = 2

1-1/k^2

1- 1/(2)^2

1-1/4

(4-1)/4 = 3/4 = 0.75

at least (20)(.75) = 15 shuttle flights lasted between 3 days and 11 days.