probability.

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by Md Raihan Uddin » Thu Mar 05, 2015 10:43 am

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by Matt@VeritasPrep » Wed Mar 11, 2015 1:11 am
Mathsbuddy wrote: P(A which is dependent on B) = P(B and then A) = P(B independent) * P(A independent)
Think of it this way instead. The chances are .68 that B increases. If B increases, then there is a (.54/.68) chance that A increases. If B does NOT increase, then the chance that A increases is 0. (In your terms, P(B) = .68 and P(A|B) = .54/.68 and P(A|~B) = 0, so P(A) = .68*(.54/.68) + .68*0 = .54.)

This gives you both probabilities in the original prompt, as well as a .32 chance that neither event occurs.