00:01
Okay, we are told here that the speed of the cars follows a normal distribution.
00:07
In other words, the usual l -shaped curve, which looks like this.
00:13
The mean is always in the middle.
00:16
So we know here is 61 miles per hour.
00:20
And we are told the silent deviation is 5 miles per hour.
00:24
I want to work out the chance that a car is traveling slower than 54 miles per hour.
00:31
Over here, somewhere is 54 miles per hour.
00:36
Now, the area under a normal curve, this area in green here, is always one.
00:43
So if i work out the area just below 54, this area here, that's the chance that a car is going slower than 54 miles per hour.
00:55
And to find that area, all i need do is use the function called normal cdf.
01:04
On a ti -84 class calculator.
01:09
So normal, okay, this new board is not working very well...