Question

PrintTech, Inc. is introducing a new line of ink-jet printers and would like to promote the number of pages a user can expect from a print cartridge. A sample of 10 cartridges revealed the following number of pages printed. (Use t Distribution Table.)

3,311	2,743	2,471	2,562	2,525	2,701	2,530	2,610	4,055	2,900

What is the point estimate of the population mean? (Round your answer to 2 decimal places.)

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

Answer 1

The point estimate of the population mean = = (3311 + 2743 + 2471 + 2562 + 2525 + 2701 + 2530 + 2610 + 4055 + 2900)/10 = 2840.8

Sample standard deviation(s) = sqrt(((3311 - 2840.8)^2 + (2743 - 2840.8)^2 + (2471 - 2840.8)^2 + (2562 - 2840.8)^2 + (2525 - 2840.8)^2 + (2701 - 2840.8)^2 + (2530 - 2840.8)^2 + (2610 - 2840.8)^2 + (4055 - 2840.8)^2 + (2900 - 2840.8)^2)/9) = 493.52

df = 10 - 1 = 9

With 9 df and 99% confidence interval the critical value is t^* = 3.25

The 99% confidence interval for population mean is

= 2840.8 +/- 3.25 * 493.52/

= 2840.8 +/- 507.21

= 2333.59, 3348.01