00:01
So this question we're given a table and we're asked to find some probabilities.
00:06
So the first one is the probability of selecting a student who spent the money given that they were given four quarters.
00:16
So what's the probability of purchasing gum given that they got four quarters? well, that's the probability of purchasing gum and getting four quarters divided by the probability of getting four quarters.
00:35
But that's just the number that got gum and four quarters divided by the total number, divided by the number that got four quarters divided by the total number.
00:56
But so the total numbers are going to cancel out here.
01:01
So you just get the number that got gum and four quarters divided by the number that got four quarters.
01:09
So the number that got gum and four quarters is this number here, that's 29.
01:16
And the number that got four quarters is that number plus the number that kept the money but were given four quarters.
01:23
So that's 29 plus 13, which is 42.
01:29
So this probability is 29 divided by 42 or approximately 0 .6905...