SOLUTION: Suppose a coin is flipped 15 times. Let X = the number of tails that are observed. Find E(X). <----Expected Value

That's the same as the mean of a binomial event with

n=15, p=

E(X) = mean(X) = np =  = 

[Even though you would never really EXPECT to ever get  tails,
that's about what you would expect to AVERAGE getting, if, say, you
flipped the coin 15 times every day for several years, and kept a running
average of how many tails you got daily.]

Edwin