If X is a discrete random variable having a probability mass function p(x), the expectation or the
expected value of X, denoted E[X], is defined to be
A biased coin is tossed until “heads” appears for the first time. If the probability of a “head” for
the coin is 2
5 , the expected number of tosses needed to get “heads” for the first time is given b
the summation is from n=1 to infinite.
Compute the expected value. (the expected value need not be an integer.)
The Attempt at a Solution
First I found the number of tosses needed to get heads, but I don't understand how to interpret this in the E[X] formula.
I know that my
what is my x ? "tails for the first time" ? how to translate it in a numerical representation ?
and the summation is from n=0 to n=2.5 ??