In a large-scale computerized multi-state exam for high school students, an erro

Question

In a large-scale computerized multi-state exam for high school students, an error within the testing system used to generate questions might fail. In a system currently used the probability of failure is 0.10, and is independent of each time the system is used. Let the random variable be the number of failures of the testing system. Find the variance of the random variable if 20 exams are administered. Retain as many decimal places as possible and round your final answer to at least 3 decimal places.

Explanation / Answer

Note that this is a binomial process, and for binomial variables,

Variance = np(1-p)

as n = 20, p = 0.10,

variance = 20*0.10*(1-0.10) = 1.8 [ANSWER]

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