00:01
Hey there, welcome to numerate.
00:02
We're giving a sample of 150 students and we are assuming this population of iq of students is normally distributed.
00:12
Okay, so we have an average and mean of 115 and a population standard deviation of 10.
00:18
We use a 90 % on confidence level to find the confidence interval for the mean.
00:25
Okay, so for this this will be the equation.
00:28
And the only value we're missing is z critical.
00:32
Okay, we're given the sample size mean a standard deviation.
00:37
So let's pull our table and match our critical value based on our significance level of 0 .10 because we have 90 % confidence interval.
00:49
And we can find our critical value.
00:54
A degrees of freedom is also, so 150 minus 1.
01:01
So it's going to be 149.
01:06
Okay, let's find critical.
01:08
Our critical will be about 1 .64.
01:14
Perfect.
01:16
And then we can plug it in.
01:18
So we will get a confidence interval equals our mean.
01:22
So our mean in this case, 115 plus and minus our z critical, 1 .64...