Question

In a site 6 blue,10 white, and 5 black marks. Two marks are selected
a progression that being 1 blue and 1 white. Find the following probability:
(1) if the first mark is replaced. (2) if the first mark is not replaced

Answer 1

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Answers are in bolded with all calculations provided below

We are given that the Total marks is equal to 6 blue +10 white +5 black = 21 marks.

Lets use this info to answers the 2 parts.

1)

P(getting 1 blue, and 1 white mark if 1st mark is replaced)

= (6/21)*(10/21) [after the 1st draw is replaced we are still left with 21 total marks]

= 0.1361

2)

P(getting 1 blue, and 1 white mark if 1st mark is NOT replaced)

[after 1st draw we are left with only 20 marks , with 1 blue mark already withdrawn]

= (6/21)*(10/20)

= 0.1429