Suppose the investigators had made a rough guess of 185 for...

Name: suppose the investigators had made a rough guess of 185 for the value of s before collecting data what sample size would be necessary to obtain an interval width of 53 ppm for a confidence l 51114
Uploaded: 2022-06-17T01:48:48-08:00
Duration: 4 min 30 s
Channel: Teresa Wray
Description: suppose the investigators had made a rough guess of 185 for the value of s before collecting data what sample size would be necessary to obtain an interval width of 53 ppm for a confidence l 51114

Suppose the investigators had made a rough guess of 185 for the value of s before collecting data. What sample size would be necessary to obtain an interval width of 53 ppm for a confidence level of 95%? (Round your answer up to the nearest whole number.)

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Transcript

00:02 Okay, so, march navarer, we have 48 kitchens and we're measuring co2 outputs, parts per million.

00:11 And the problem b part says one if beforehand, they guesstimated that s was going to be about 180, and we want our confidence interval to be about 44 parts per million for a 95 % confidence interval.

00:31 How many people would we need or how many kitchens would we need to survey? so really, for part b of the question, we don't need any of this information at all because we're going back in time and assuming we haven't done any tests or done any sampling or anything.

00:53 So in order to do that, we need to have an s and a margin of error.

01:01 And the z star.

01:03 Well, we have our s.

01:05 It's 180.

01:07 And we almost have a margin of error.

01:10 So this wants to be the entire interval width.

01:14 So pretend this is the interval.

01:17 We want that whole thing to be 44 parts per million.

01:21 Remember that a margin of error is added or subtracted.

01:26 So this is going to be the below the mean and above the mean.

01:30 So we we need to divide this in half and have 22 and 22.

01:39 So our margin of error that we want to be smaller than is going to be 22 parts per million.