1.

The probability that a person who undergoes kidney operation will recover is 0.5. Find the probability that of the six patients who undergo similar operations.a. None will recover. b. Half of them will recover.

Answer»

Since, there are six patients

n = 6 

p = P(success) = 0.5 and q = 1 - p = 0.5 

X ~ B(n = 6, p = 0.5) 

The p.m.f. of x is given as P(X = x) = nCx(p)x (q)n-x

P(X = x) = P(x) = 6Cx (0.5)x (0.5)6-x

x = 0, 1, 2, 3, 4, 5, 6

a. P(none will recover) 

P(X = 0) = 6C0 (0.5)0 (0.5)6-0 

= (1) (1) (0.5)6

= 0.015625

b. P(half of them will recover)

P(X = 3) = 6C3 (0.5)3 (0.5)6-3 

\(\frac{6!}{3!.3!}\) (0.5)3 (0.5)3 

= \(\frac{6\times5\times4\times3!}{3\times2\times1\times3!}\)(0.125) (0.125) 

= 20 x 0.015625 

= 0.3125



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