00:01
So we have scores that are from zero, which they would say and say between from zero to 100.
00:07
However, we're told that zero to 50 never occurs and we're having 51 to 100 are equally likely.
00:22
Equally likely and we also know we also know that the probability of getting an a and a is well we're going to find that probability about a is a score of 90 to 100 a b is 80 to 89 a c is 70 to 79 and a d is a 60 to 69 and we know that the failing grades, fs, are going to be scores.
01:02
Really, there are scores of anything below that, but they would have to be scores of 51 to 59.
01:10
So we want to answer some questions.
01:12
And we're told the first question is we want to find the probability of having s sub 100.
01:20
And so i'm assuming that means that you get a score of 100.
01:24
And so let's see if we have the numbers 51 to 100 occur if we take the difference plus one.
01:31
That's how many numbers there are.
01:33
So you could get fooled here and think that there are only 49 numbers here plus one.
01:38
There are 50 numbers from 51 to 100, including the end points.
01:44
So we take like zero to 100 is actually 101 scores could have been obtained going from zero to 100.
01:55
So this problem.
01:56
Is it's one number out of 50.
02:00
So for part b, we wanted to define what was the probability that someone gets an a.
02:08
Well, there are 50 numbers available and 90 to 100 is 11 numbers.
02:15
So that difference plus one.
02:18
So there are 11 numbers from there.
02:20
So if you want it at a decimal, this one's going to be 0 .02...