Question

4.37) A set of data whose histogram is extremely skewed yields a mean and standard deviation of 70 and 12, respectively. What is the minimum proportion of observations that

Answer 1

75%

88.89%

Explanation:

Given :

Mean = 70

Standard deviation = 12

Since the data is said to be extremely skewed, we apply Chebyshev's theorem rather than the empirical rule :

The minimum proportion of observation between 46 and 94

Chebyshev's theorem :

1 - 1 / k²

k = number of standard deviations from the mean

k = (94 - 70) / 12 = 24 / 12 = 2

Hence, we have ;

1 - 1/2²

1 - 1/4

1 - 0.25 = 0.75

Hence, The minimum proportion of observation between 46 and 94 is 75%

Between 36 and 106 :

k = (106 - 70) / 12 ;

k = 36/12 = 3

Hence,

1 - 1/3² = 1 - 1/9 = 8/9 = 0.8888 = 88.89%

The minimum proportion of observation between 34 and 106 is 88.89%