0:00
All right.
00:01
In your question, you're given probabilities for ordering a beverage or a drink, probability for ordering food, probability of ordering beverage or food.
00:12
Okay, so this is a perfect situation for a bend diagram because there's going to be some overlap here.
00:19
Some people ordered a drink, also ordered food, and so on.
00:23
So i'm going to start with probability of a or b.
00:27
And basically what i know is that the three regions of these two circles, we have the overlap region and the non -overlap regions, would have to add up to that .98 total.
00:40
But i can't just put .645 in for a and 0 .45 in for b because that totals over 100%, which is not possible.
00:50
So i'm going to use the formula for a probability of a or b, and it looks like, usually this is like a u -shaped symbol.
01:02
And the way we find that is the probability of a plus the probability of b minus the probability of a and.
01:15
Okay, so we know this.
01:17
That was given to us as 0 .98, and we know probability of a is 0 .65, probability of b is 0 .45, and we don't know this value, probability of a and b.
01:34
Okay, so what i end up with here is these two values would add up to 1 .1.
01:45
So let me work this over here a little bit.
01:54
All right, so i would subtract 1 .1, just on a little algebra here, and we end up with a negative .12 equals negative probability of a and b...