1. You want to obtain a sample to estimate a population mean. Based on previous

Question

1. You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately =77.1=77.1. You would like to be 98% confident that your esimate is within 1 of the true population mean. How large of a sample size is required?

2.You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately =62.7=62.7. You would like to be 98% confident that your esimate is within 4 of the true population mean. How large of a sample size is required?

n =



Do not round mid-calculation. However, use a critical value accurate to three decimal places — this is important for the system to be able to give hints for incorrect answers.

Explanation / Answer

1)

Population standard deviation =77.1

Margin of Error E=1

At 98% confidence critical z=2.326

So, sample size >=(Z*/E)2 = (2.326*77.1/1)2=32160.90

Hence required sampel size n=32161

2)

Population standard deviation =62.7

Margin of Error E=4

At 98% confidence critical z=2.326

So, sample size >=(Z*/E)2 = (2.326*62.7/4)2=1329.34

Hence required sampel size n=1330

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