00:01
Hi, i'm david and i'm here to help you answer your question.
00:04
Now let me bring up your question here.
00:06
In this question we want to discuss about the condition in that you use the central limit theorem.
00:13
Here we have the iq score normally distributed with the mean equal to 100 and standard division equal to the 16.
00:21
So we have the x followed by the normal with the mean equal to 100, standard division equal to the 16.
00:28
In the a, calculate the probability that the random chosen has iq more than 120.
00:36
Here, to do the part a, 25 probability that the iq will be more than 120.
00:44
We need to turn the x into the z.
00:48
To do that, we will know the formula that x minus mean of a standard deviation.
00:53
We follow by the standard normal.
00:55
Therefore, we have to turn the 120, we minus the mean.
00:58
Over the standard deviation.
01:02
And then we get equal to the z will be greater than 20, we divide by 16, equal to the 1 .25.
01:12
By symmetry doesn't equal to the proper picture the z smaller than minus 1 .25.
01:18
Let me bring up the z table, and i will show you how to use the z table here.
01:25
Let me put the table down here for you.
01:28
Now from the table, we have the z score equal.
01:31
To the minus 1 .2, 5.
01:35
So the corresponding probability equal to the 0 .156.
01:43
And that's will be the probability for the a...