There are 20 tiles in a bag. Of these, 9 are purple, 5 are black and the rest are white.

Event A= drawing a white tile on the first draw

Event B= drawing a Black tile on the second draw

If two tiles are drawn from the bag one after the other not replaced, what is P(B|A) expressed in simplest form?

A. 1/4

B. 5/19

C. 3/10

D. 9/20

Respuesta :

[tex]P(B|A)=\dfrac{P(A\cap B)}{P(A)}\\\\ |\Omega|=20\cdot19=380\\ |A|=6\cdot19=114\\ |A\cap B|=6\cdot5=30\\\\ P(A)=\dfrac{114}{380}=\dfrac{3}{10}\\ P(A \cap B)=\dfrac{30}{380}=\dfrac{3}{38}\\\\ P(B|A)=\dfrac{\dfrac{3}{38}}{\dfrac{3}{10}}\\\\ P(B|A)=\dfrac{3}{38}\cdot\dfrac{10}{3}=\dfrac{5}{19}\Rightarrow \text{B} [/tex]

Answer:

B

Step-by-step explanation: