00:01
Ok, the first one is for the population.
00:04
So we have here x and the usual normal curve like this, the bell -shaped curve, with the mean in the middle, 179 .5, and your standard deviation of 22.
00:24
Now the key thing with a normal curve is the area underneath, this area in green, will always be 1.
00:32
Now i want to work out the chance that it lies between 174 .5, so over here somewhere, and 176 .4, which will be there, 176 .4.
00:51
I want to find this green area here, and that's the answer basically.
00:58
And to find that, what we do is use the function called normalcdf that you will find on all graphing calculators.
01:07
On the ti -84 +, just press 2nd, followed by vars by the arrow keys on the right, and that gives the menu for distributions.
01:20
Number 2 on the list is normalcdf, and lower is 174 .5, this number here, upper 176 .4, that covers the green area.
01:33
The mean is 179 .5, standard deviation is 22.
01:39
That's the input into the calculator.
01:45
And that will be 0 .03386.
01:53
What they want here is, one second, four places, so 0 .03386, 0 .0339 is the answer we need.
02:10
Now that's for the entire population...