00:01
For this exercise, we were told that the time to find a parking space at 9 a .m., we'll call that random variable x, is normally distributed with a mean of 5 minutes, and standard deviation of 2 minutes.
00:14
And we are asked for 80 % of the time it takes more than how many minutes to find a parking space.
00:23
Mathematically, it's saying this.
00:25
Probability of taking longer than this amount of time is .80.
00:31
So there is some duration to find the parking space such that the probability of taking longer than that duration is 0 .8.
00:46
This can be re -expressed in terms of a cumulative probability.
00:51
So this means that the probability that of taking less than or at most of that time is 0 .2.
01:03
If 80 % of the time it takes more than x minutes, then 20 % of the time it will take.
01:10
At most x minutes.
01:13
Now we can find this value of time or of x using software...