ShmoopTube

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And here's your shmoop du jour brought to you by dough..You can

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need it or you can need it...On Sundays many people are finding their way [Child pestering Dad while on a laptop]

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downtown to Benjamino's bakery all craving donuts the Baker at Benjamino's [People walking towards Benjamino's bakery]

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brought in a statistician to calculate a confidence interval for the average

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number of donuts each person bought on a Sunday. 100 people were surveyed and the

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mean number of donuts bought was 3.84 with a standard deviation of 1.12 and

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the confidence interval he received was 3.6205 by 4.0595. What

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was the confidence level that the statistician used in the interval? All

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right here the potential answers....Well if you calculate using the lower limit of

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3.6 205 the mean of 3.84 and 1.12 is the standard deviation while your formula [maths formula on a piece of paper]

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looks like this the Z value equals 1.96 so where does that equate in the Z table

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at the ninety percent confidence level no. Not at the 97 98 or 99 percent levels [Teacher pointing to confidence levels]

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either that leaves B; It's a 95 percent confidence level and yeah that's

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the correct answer once again proving that knowing your Z table like the back

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of your hand is your avenue to success with stats. Hopefully this donut problem [Man holding hand up with Z table on his palm and kid eating a doughnut]

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made sense to you and you're not sitting there with a glazed look in your eyes..

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