00:01
In this problem, we are given the two z scores, which are minus z and plus z, and the area between these two z scores, let's represent that with the letter a, that is equal to 0 .9994.
00:16
And we have to determine the value of the z score, which is represented by the letter z.
00:21
So we will consider this to be represented by z star instead, so as to distinguish this from the standard regular, not normal random variable z.
00:31
And that means these two z scores will be minus z star and plus z star.
00:35
And the area between these two z scores, that is 0 .9994.
00:41
So that means the probability that the z score is more than minus z star, but less than z star, this will be equal to 0 .9994.
00:51
So that implies twice the probability that the z score is greater than 0, but less than z star, this will be equal to 0 .9904...