Question

A sample of 49 observations is taken from a normal population with a standard deviation of 10. The sample mean is 55. 

Determine the 99% confidence interval for the population mean. (Round your answers to 2 decimal places.) 

Confidence interval for the population mean is _______ and _______ .

A research firm conducted a survey to determine the mean amount Americans spend on coffee during a week. They found the distribution of weekly spending followed the normal distribution with a population standard deviation of $5. A sample of 49 Americans revealed that X̅ = $20. 

a. What is the point estimate of the population mean?

b. Using the 95% level of confidence, determine the confidence interval for u. (Round your answers to 2 decimal places.) 

Answer 1

ElO- ) Solutions Given n=49 6=10 X=55o. gg.% confidence internal for the Construct mean population 6.5 = (x + Za ( 6 ) =(5s + Zool ( 10 ) = let za = Zool _ Zooos= 2.576 by table z

= (ss [ 2576 (H)) (5st 3.68) =(55–368 , 5573.68 ) = (51:32 , 58.68 ) lorentini confidence interval for the populatiun mean 51:32 and 58.68 Giren X = $ 20 6= $5 n=49 point estimate of the population mean Estimated population means 20 Construct 95 7. confidence internal for the el C. I = (x + 2a ( 6 ) =(20 + Zoos ( 3 ) let zay - Zoos = 20.025 = 1.96 by table

= ( 2011:96 ()) 49 = (20 + 1.4) = (18.6 , 21.4) te confidence interval for the population mean is (18.6) and 1214 |