# STAT Formative Assessment #6

## Quiz by JONALD ROSARIO

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5 questions
• Q1

A company president wishes to estimate the average number of hours his part-time employee per week. The standard deviation from a previous study is 9.3 hours. How large a sample must be selected if he wants to be 99% confidence of finding whether the true mean differs from the sample mean by 4 hours

n = 36

n = 39

n = 38

n = 37

30s
• Q2

Let us imagine that you own a fast-food company. You are doing a survey to get an idea of how long customers stay in a restaurant. In the past two years, it was observed that the standard deviation of the time they stay in a restaurant is restaurant is 12 minutes. How many people do you need to observe so that the desired margin of error will not be more than three (3) minutes with a confidence level of 95%?

n = 78

n = 62

n = 89

n = 45

30s
• Q3

A school principal wants to estimate the average score of their students on a standardized test. The standard deviation from a previous study is 12 points. How large a sample must be selected if they want to be 95% confident of finding whether the true mean differs from the sample mean by 6 points?

n = 15

n = 18

n = 12

n = 70

30s
• Q4

A researcher wants to estimate the average weight of newborn babies in a certain region. The standard deviation from a previous study is 0.5 kilograms. How large a sample must be selected if they want to be 90% confident of finding whether the true mean differs from the sample mean by 0.2 kilograms?

n = 17

n = 15

n = 30

n = 10

30s
• Q5

A city council is interested in estimating the average monthly water consumption per household. The standard deviation from a previous study is 20 gallons. How large a sample must be selected if they want to be 99% confident of finding whether the true mean differs from the sample mean by 5 gallons?

n = 112

n = 107

n = 180

n = 121

30s

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