00:01
So this question says that suppose the tennis player in the previous exercise serves 80 times in a march.
00:08
What does it mean and the standard deviation of the number of good first serve expected? that's the first question.
00:17
So the probability that a certain tennis player makes a successful first serve is 0 .70 according to the question.
00:36
So i'm going to say let x be the number of successful first seven.
00:56
So the total number of size is, total number of stars is equal to 80, right? so therefore, x follows binomial, which is n is equal to 80, which is total number, p is equal to 0 .7, which is the probability.
01:31
So now to the first question, the mean and the standard deviation of the number of good first set expected.
01:41
So the mean number, which is summation x, b equals to n p, and this is equal to 80 because n is 80, multiplied by 0 .7, and this equals to 56.
01:59
So the mean is 56...