Question

It is known that 1% of the products of a company are defective. By Poisson distribution, the probability that a sample of 20 products contain exactly two defectives is

• A. (0.02) e^-0.2
• B. (0.2) e^-0.2
• C. (0.02) e^-0.02
• D. (0.2) e^-0.02

Answer 1

Answer: (A)

(0.02) e^-0.2

Answer 2

n = 20 P = 1/100 λ = np = 1/5

P(X=2) = $\frac { \lambda ^ { 2 } } { \angle 2 } \mathrm { e } ^ { - \lambda } = \frac { \frac { 1 } { 25 } } { 2 } \mathrm { xe } ^ { - 1 / 5 } = \frac { 1 } { 50 } \mathrm { e } ^ { - 1 / 5 }$

= 0.02 x e^-0.2