perplexus.info :: Probability : Four balls

Four balls (Posted on 2017-05-19)

There are four balls in a hat: a blue one, a white one, and two red ones. Now I draw simultaneously two balls, look at them, and announce that at least one of them is red.

What is the chance that the other is red as well?

See The Solution Submitted by Ady TZIDON

Rating: 3.5000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)

I agree with Brian

| Comment 4 of 22 |

The chance that they are both red = 1/6.

The chance that at least one is red = 1 - 1/6 = 5/6

1/6 divided by 5/6 = 1/5.

Posted by Steve Herman on 2017-05-19 13:28:44

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