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QUESTION

# A simple random sample of 25 recent graduates from a particular collage gives a sample mean starting salary of \$24,000 with sample standard deviation...

1.A simple random sample of 25 recent graduates from a particular collage gives a sample mean starting salary of \$24,000

with sample standard deviation \$3,000.

(a) Give the 95% confidence interval.

(b) Without doing any calculations, would the 99% confidence interval be narrower or wider than the 95% confidence

interval.

(c) Suppose the sample size was 50 (instead of 25) and the sample mean and standard deviation were the same values.

Without doing any calculations, would the 95% confidence interval with n = 50 be narrower or wider than the 95% confidence interval with n = 25?

2.We take a simple random sample of size 50 from a population with unknown variance. We find the sample mean is ̄x= 25 and the sample standard deviation is s = 15.

(a) Give the 90% confidence interval for the population mean μ .

(b) Give the 95% confidence interval for the population mean μ .

(c) Give the 99% confidence interval for the population mean μ .