You have ABCDEFGHIJ you chose at random Whats the probabilit

You have A,B,C,D,E,F,G,H,I,J you chose at random. Whats the probability you chose A,B,C? You chose A on the first try. What\'s the probability you chose B,C?

Solution

1.

There are 10 letters here, and you choose 3.

There are

10P3 = 720 ways to choose 3 letters from A to J.

Only 1 of those is A, B, C.

Thus,

P(A, B, C) = 1/720. [ANSWER]

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2.

As A is already the first try, there are only 9 letters to choose for the next two options.

Thus, there are 9P2 = 72 ways to choose the next two.

Only 1 of those is B,C.

Thus,

P(B,C|A) = 1/72 [ANSWER]