Finding μ, σ, and Unusual Values. In Exercises, assume that a procedure yields a binomial distribution with n trials and the probability of success for one trial is p. Use the given values of n and p to find the mean μ and standard deviation σ . Also, use the range ruh of thumb to find the minimum usual value μ – 2σ and the maximum usual value μ – 2 σ.

Guessing on ACT Random guesses are made for the 60 multiple-choice questions on the math portion of the ACT test, so n = 60 and p =1/5 (because each question has possible answers of a, b, c, d, e, and only one of them is correct).

Answer :

Step 1 of 2 :

Given, Guessing on ACT Random guesses are made for the 60 multiple-choice questions on the math portion of the ACT test, so n = 60 and p =⅕.

The procedure yields a binomial distribution.

Where, mean = = np = 60(1/5)

= 12

Variance = npq

= (60)(0.2)(0.8)

= 9.6

Standard deviation = =

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