Homework SourseIt has been observed that 20 of the examinees on a driving t
It has been observed that 20% of the examinees on a driving test fail.
a.) Assume people take the exam one at a time. What is the exact probability that the third person is the first to fail.
b.) 50 people take the exam. What is the approximate probability that 7 or more of them fail.
It has been observed that 20% of the examinees on a driving test fail.
a.) Assume people take the exam one at a time. What is the exact probability that the third person is the first to fail.
b.) 50 people take the exam. What is the approximate probability that 7 or more of them fail.
a.) Assume people take the exam one at a time. What is the exact probability that the third person is the first to fail.
b.) 50 people take the exam. What is the approximate probability that 7 or more of them fail.
Solution
A)
P(pass,pass,fail) = (1-0.20)*(1-0.20)*0.20 = 0.128 [ANSWER]
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b)
Note that P(at least x) = 1 - P(at most x - 1).
Using a cumulative binomial distribution table or technology, matching
n = number of trials = 50
p = the probability of a success = 0.2
x = our critical value of successes = 7
Then the cumulative probability of P(at most x - 1) from a table/technology is
P(at most 6 ) = 0.103398227
Thus, the probability of at least 7 successes is
P(at least 7 ) = 0.896601773 [ANSWER]
