00:01
Okay, we are told that the variable follows a normal distribution.
00:05
That means the usual l -shaped curve like this, x along here.
00:13
Now the mean is always in the middle and the asymmetry about the mean, the standard deviation we're told is 4.
00:22
And the key thing about a normal curve is the area underneath here, the green, is always going to be 1.
00:30
Now what i want to work out is the chance that x is going to be less than 83.
00:38
Down here, p of x less than 83.
00:46
All we do, mark 83 on the diagram like this and find the area below 83 and that's the answer.
00:57
And to find that use the function normalcdf on the ti -84 plus calculator or one similar.
01:06
That you will find by pressing 2nd followed by vars, v -a -r -s on the right by the arrow keys.
01:14
That gives the menu for distributions...