00:01
Here we are given a random variable x which is equal to the number of heads in four independent flips of a coin.
00:07
And we are asked under certain assumptions to determine the probability mass function of x and compute the probability that x is equal to an odd number.
00:17
Now let's make a couple of assumptions here.
00:26
Flips are independent, so that means the outcome for one flip has no bearing on the outcomes for the other flips.
00:40
And let's also assume that it's a fair coin.
00:42
So that means the probability of getting a head on any flip is exactly one half.
00:56
Now here each flip can be viewed as a bernoulli trial.
00:59
There's two outcomes of interest, it's either a head or it's not.
01:03
And since each flip is independent, or since the flips are independent from each other, then the number of successes in a given number of independent brunile trials is a binomial random variable.
01:15
So we can say that the number of heads in four flips of the coin is a binomial...