- #1

sanctifier

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## Homework Statement

There are 3 boxes containing some products of same type.

Box 1 contains 10 products and 3 of them are flawed.

Box 2 contains 15 products and 7 of them are flawed.

Box 3 contains 25 products and 5 of them are flawed.

Randomly choose one box from the 3 then draw one product from the chosen box, continue to draw one product from rest products in the chosen box, i. e., drew product will not be returned to the box.

Question 1 : What is the probability that the 1st drew product is a flawed one?

Question 2: What is the probability that the 1st drew product is a flawed one if we know the 2nd drew product is unflawed?

## Homework Equations

Nothing special.

## The Attempt at a Solution

Answer 1:

[itex] p= \frac{1}{3} \frac{3}{10} + \frac{1}{3} \frac{7}{15} + \frac{1}{3} \frac{5}{25} [/itex]

Answer 2:

[itex] p= \frac{1}{3}* \frac{ \frac{3}{10} \frac{7}{9} }{ \frac{7}{10} \frac{6}{9} +\frac{3}{10} \frac{7}{9}} +\frac{1}{3}* \frac{ \frac{7}{15} \frac{8}{14} }{ \frac{8}{15} \frac{7}{14} +\frac{7}{15} \frac{8}{14}} +\frac{1}{3}* \frac{ \frac{5}{25} \frac{20}{24} }{ \frac{20}{25} \frac{19}{24} +\frac{5}{25} \frac{20}{24}} [/itex]

Are these answers correct? Thank you in advance!