Find the population mean if the population standard deviati

Find the population mean , if the population standard deviation = 18. (Round \"z\" value to 2 decimal places and final answer to 1 decimal place.)

Find the population mean , if the population standard deviation = 27. (Round \"z\" value to 2 decimal places and final answer to 1 decimal place.)

Find the population standard deviation , if the population mean = 131. (Round “z” value to 2 decimal places, and final answer to 2 decimal places.)

Find the population standard deviation , if the population mean = 115. (Round “z” value to 2 decimal places, and final answer to 2 decimal places.)

Solution

a)

If the right tailed area is 0.09, the the corresponding z score, by table/technology, is

z = 1.340755034

Thus, as

u = x - z * sigma

Then

u = 149 - 1.340755034*18 = 124.8664094 [ANSWER]

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b)

If the right tailed area is 0.09, the the corresponding z score, by table/technology, is

z = 1.340755034

Thus, as

u = x - z * sigma

Then

u = 149 - 1.340755034*27 = 112.7996141 [ANSWER]

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c)

As

sigma = (x - u) / z

Then

sigma = (149 - 131)/1.340755034 = 13.42527124 [ANSWER]

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As

sigma = (x - u) / z

Then

sigma = (149 - 115)/1.340755034 = 25.35884568 [ANSWER]