A college professor wants to know the amount of time in hours per week that stud

Question

A college professor wants to know the amount of time in hours per week that students spend doing homework at her university. From a previous study it is known that the standard deviation is 5.4 hours per week How large will a sample have to be in order to construct a 90% confidence interval that the true mean differs from the sample mean by at most 1 hour? 77 78 50 45 A random sample of size 16 taken from a normal population has a sample mean equal to 122 and the sample standard deviation is 8.2. Find a 95% confidence interval for the population standard (36, 692, 161 067) (6.057 12, 691) (6.35, 1179) (40.368, 138.906)

Explanation / Answer

answer 1 :Standard deviation is 5.4 ,

For 90% confidence, the z value is 1.645

we are given that the margin of error is 1

therefore 1=1.645*(5.4)/sqrt(n)

sqrt(n)=8.88

or n=79, optionB

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