Thread: Not understanding answer...

The question posed is: "Suppose you flip a coin n times. If you win a dollar every time the coin comes up heads and lose a dollar every time it comes up tails, what is the probability that you will win k dollars?"

The answer given is: "If 2 doesn't divide , the probability is 0. If 2 does divide , the probability is "

Does this make sense to anyone?

Originally Posted by earachefl

The question posed is: "Suppose you flip a coin n times. If you win a dollar every time the coin comes up heads and lose a dollar every time it comes up tails, what is the probability that you will win k dollars?"

The answer given is: "If 2 doesn't divide , the probability is 0. If 2 does divide , the probability is "

Does this make sense to anyone?

To win k dollars requires n1 wins and n2 losses such that n1+n2=n, and
n1-n2=k.

This last imples that 2 n1 - (n1+n2) = k, so:

2 n1 = k+n

Hence k+n is even so the probabilty of winning k dollars in n trials is 0 if k+n is odd.

Also if k+n is even then the number of wins is (k+n)/2, and the probability of this is:



RonL

So they did leave out part of the answer:

which does make sense. Thanks!