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The probability that a patient recovers from a delicate heart operation is 0.8.
What is the probability that
(a) exactly 2 of the next 3 patients who have this operation survive?
(b) all of the next 3 patients who have this operation survive?
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It is the binomial distribution problem.
The probability of success for any/each individual trial is p = 0.8.
So, apply the standard binomial distribution formulas for probabilities.
(a) The number of trials n = 3; the number of successful trials k = 2.
P(n=3; k=2, p= 0.8) = = = 0.384. ANSWER
(b) The number of trials n = 3; the number of successful trials k = 3.
P(n=3; k=3; p= 0.8) = = 0.512. ANSWER
Solved in full.