# The probability that a certain kind of component will survive a check test is 0.5. Find the probability that exactly two of the next four components tested will survive. - Mathematics and Statistics

Sum

The probability that a certain kind of component will survive a check test is 0.5. Find the probability that exactly two of the next four components tested will survive.

#### Solution

Let X = number of tested components survive.

p = probability that the component survives the check test

∴ p = 0.6 = 6/10 = 3/5

∴ q = 1 - p = 1 - 3/5 = 2/5

Given: n = 4

∴ X ~ B(4, 3/5)

The p.m.f. of X is given as:

P[X = x] = "^nC_x  p^x  q^(n - x)

i.e. p(x) = "^4C_x (3/5)^x (2/5)^(4 - x)

P (exactly 2 components survive)

= P[X = x] = p(2)

= "^4C_2 (3/5)^2 (2/5)^(4 - 2)

= ((4 xx 3)/(1 xx 2)) xx (3/5)^2 (2/5)^2 = (6 xx 9 xx 4)/625

= 216/625 = 0.3456

Hence, the probability that exactly 2 of the 4 tested components survive is 0.3456.

Concept: Binomial Distribution
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#### APPEARS IN

Balbharati Mathematics and Statistics 2 (Arts and Science) 12th Standard HSC Maharashtra State Board
Chapter 8 Binomial Distribution
Miscellaneous exercise 8 | Q 9 | Page 524