The manufacturer of a new line of ink-jet printers would like to include as part
ID: 3379545 • Letter: T
Question
The manufacturer of a new line of ink-jet printers would like to include as part of its advertising 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 Student's z Distribution Table.) 3,360 2,450 2,550 2,610 2,730 2,610 2,550 3,320 3,390 2,400
a. What is the point estimate of the population mean? (Round your answer to the nearest whole number.) Estimated population mean
b. Develop a 90% confidence interval for the population mean. (Round your answers to 2 decimal places.) Confidence interval for the population mean is between and .
Explanation / Answer
a)
It is the sample mean,
X = sample mean = 2797 [ANSWER]
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b)
Note that
Lower Bound = X - t(alpha/2) * s / sqrt(n)
Upper Bound = X + t(alpha/2) * s / sqrt(n)
where
alpha/2 = (1 - confidence level)/2 = 0.05
X = sample mean = 2797
t(alpha/2) = critical t for the confidence interval = 1.833112933
s = sample standard deviation = 396.7380888
n = sample size = 10
df = n - 1 = 9
Thus,
Lower bound = 2567.018386
Upper bound = 3026.981614
Thus, the confidence interval is
( 2567.018386 , 3026.981614 ) [ANSWER]
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