00:01
In this question for part a, we are asked for the proportion of observations from the standard normal distribution that take values less than z equals 1 .17.
00:11
So that is the probability that z is less than 1 .17.
00:16
And we can find this in the standard normal table by looking up 1 .17, which corresponds to the cell, which is .8790, which at two decimal places is .88, which is the answer that you have found.
00:38
The proportion of observations that take values larger than minus .74.
00:54
So this is equal to 1 minus probability that z is less than or equal to minus .74.
01:05
And we can look this up in a standard normal table as well.
01:10
So minus .74 corresponds to a cumulative probability of .2296, which is .7704.
01:32
0 .704, or approximately 0 .77.
01:38
So the correct answer here is d, a for the first one.
01:52
And then for c we are told that iq scores are approximately normal with the mean of 100 and standard deviation of 15.
02:06
And we are asked for the percent of people who score higher than 130...