(b) (i) The probability of drawing no blue marbles is, as I have shown: ... ?
(ii) There are three routes through the probability tree that correspond to two blue marbles: BWW, WBW and WWB. Work out the probabilities of each of them and add the resulting fractions together. I'll start you off with BBB:Can you complete it?
Question 2. (On an administrative note, you're asked not to post two different questions in the same thread. See Rule 14.)
There are ways of choosing a committee of people from .
If James and Sarah have been chosen, we need to choose from the remaining to complete the committee. In how many ways can this be done?
Divide the second number by the first to get the probability that James and Sarah are on a committee chosen at random.
I make the answer . Do you agree?