00:01
For this problem, we are asked which of the options will decrease the margin of error for a confidence interval.
00:24
Now, here i'll note that i'll be talking about this as if we're looking for a confidence interval for means where we have either a large enough sample size or enough information to use a z -score.
00:36
But the principle here will apply for whichever kind of confidence interval we're using.
00:41
So we have that the margin of error is going to be equal to the z -score for a one -tail proportion of our level of significance over 2 times the population standard deviation, if we have it, divided by the square root of the sample size.
00:58
I'll note here that alpha is equal to 1 minus the level of confidence.
01:03
We have that the z -score for alpha over 2 increases as alpha decreases, which then means that it increases as c increases, since we can see that alpha will decrease as the level of confidence increases.
01:36
We can also see that since we are dividing by the square root of the sample size, we you can see that increasing n results in a decrease in the margin of error...