In: Statistics and Probability
Rock band The Rolling Stones have played scores of concerts in the last twenty years. For 30 randomly selected Rolling Stones concerts, the mean gross earnings is 2.65 million dollars.
Part a) Assuming a population standard deviation gross earnings of 0.47 million dollars, obtain a 99% confidence interval for the mean gross earnings of all Rolling Stones concerts (in millions). Please carry at least three decimal places in intermediate steps. Give your answer to the nearest 3 decimal places.
confidence interval ( , )
Solution :
Given that,
= 2.65
= 0.47
n = 30
At 99% confidence level the z is ,
= 1 - 99% = 1 - 0.99 = 0.01
/ 2 = 0.01 / 2 = 0.005
Z/2 = Z0.005 = 2.576
Margin of error = E = Z/2* ( /n)
= 2.576 * (0.47 / 30)
= 0.221
At 99% confidence interval estimate of the population mean is,
- E < < + E
2.65 - 0.221 < < 2.65 + 0.221
2.429 < < 2.871
The confidence interval is 2.429 to 2.871