A lot of 10 components contains 3 that are defective. Two components are drawn at random and tested. Let A be the event that the first component drawn is defective, and let B be the event that the second component drawn is defective.

(a) Find P(A)
(b) Find P(B | A)
(c) Find P(B)

Respuesta :

Answer:(a) [tex]P(A)=0.3[/tex]

(b)[tex]P(B|A)=\dfrac{2}{9}[/tex]

(c) [tex]P(B)=0.3[/tex]

Step-by-step explanation:

Given , Number of components in a lot = 10

Number of  defective components = 3

Let [tex]A[/tex] be the event that the first component drawn is defective, and let [tex]B[/tex] be the event that the second component drawn is defective.

Probability that  first component drawn is defective=[tex]P(A)=\dfrac{3}{10}=0.3[/tex]

After first component is drawn , the total component left =9

defective component left = 2

Probability that the second component is defective given that first one is also defective : [tex]P(B|A)=\dfrac{\text{Number of bad components left}}{\text{Total components left}}=\dfrac{2}{9}[/tex]

Probability that second component drawn is defective = (First component good , second is defective+ First is defective , second is also defective)

[tex]P(B)=\dfrac{7}{10}\times\dfrac{3}{9}+\dfrac{3}{10}\times\dfrac{2}{9}=\dfrac{3}{10}=0.3[/tex]