00:01
Okay, so in these questions we're using the two -coin method, which basically is a way of sampling so that some people basically get to lie.
00:09
So you can answer sensitive questions more easily and more clearly.
00:15
So here's the formula for it.
00:17
The rate equals 4 times the total number of yeses minus n over 2n.
00:25
N.
00:26
Okay, so in question three, we have 180 students, so that's our n, and the total number of yeses is 50, right? 50 people answer yes.
00:40
So now to get the rate, we're just going to plug in those numbers into my equation.
00:45
So the rate should equal four times the total number of yeses minus minus n over 2n, right? so that's 200 minus 80 is 20 over 360, which is 10 over 180, meaning that 10 of the 180 students we would expect to actually, that's our expected number that we think actually did steal from a store, okay? for number four, it's a little bit different because we know the actual rate we have 24 students, so n equals 24.
01:23
And 20 have cheated on a test in the past...