00:01
For this problem, we know that we want to have a margin of error of no more than 5 percentage points.
00:07
So we want the margin of error to be less than or equal to 0 .05.
00:14
We're told that we have a, or that we want a 90 % confidence level.
00:23
And we are told to assume in part b.
00:26
Actually, i'll start with part a and then go to part b.
00:28
I can see you've already answered part a, but i'm just going to double check that.
00:32
So for part a, we assume that nothing is known about the percentage of adults who gamble online.
00:37
So the formula that we use for finding our required sample size, so that the required sample size will be equal to the critical z score corresponding to our level of confidence, which would be the z score for a one -tail probability of 0 .05, divided by our margin of error squared times p times 1 minus p.
00:59
That's the general formula.
01:00
If we don't have any information, then we have that p is equal to 0 .05.
01:05
That'll give us the most conservative estimate...