Sample with size n = 100 has mean = 30. Assuming the population standard deviation is 8, construct 95% confidence interval for population mean. Use formula on page 312, z?/2 = 1.96
Answer

between 28.4 and 31.6

between 27.0 and 33.0

between 26.1 and 34.2

between 24.1 and 35.9

Question 2

With sample mean x = 12.5, sample size n = 40 and population standard deviation = 4
find 99% confidence interval for population mean. Use formula on page 312 with z?/2 = 2.575
Answer

between 11.5 and 13.5

between 10.9 and 14.1

between 10.1 and 15.1

between 7.4 and 14.2

Question 3

Find t-value for sample size n = 16 and area to the right 0.10 (Use Appendix Table IV).
Answer

2.015

1.860

1.725

1.341

Question 4

For sample mean x = 150, sample size n = 36 and sample standard deviation s = 40 find 80% confidence interval for population mean. Population standard deviation is not known, you should use formula on page 328 with t-value from Appendix Table IV (use column t0.10).
Answer

135.6 to 148.4

154.2 to 175.8

141.3 to 158.7

162.3 to 187.5

Question 5

Use formula from material posted on Blackboard in for this week Lectures section to estimate population proportion. Sample proportion is ps = 0.48, sample size 125, zc = 1.96 (90% confidence level).
Answer

Which of the following is not needed to be known to calculate a confidenceinterval?
a. standard deviation
b. sample size
c. mean
d. degree of confidence

A sample of n=16 scores is obtained from an unknown population. The sample has a mean of M=46 with SS=6000.
a. Use the sample data to make an 80% confidenceintervalestimate
of the unknown population mean.
b. Make a 90% confidenceintervalestimate of μ.
c. Make a 95% confidenceintervalestimate of μ.

I need help solving 95% confidenceinterval and point estimate problems.
A sample of 16 people are used, each one is to keep track of their time with the following result in hours.
1.8, 1.7, 0.9, 1.1, 1.5, 1.5, 1.2, 0.6, 1.4, 0.9, 0.7, 1.8, 1.7, 2.2, 1.5, 1.3
Construct a 95% confidenceinterval for the amount of time n

Part A: Define (a) point estimate, (b) intervalestimate, (c) confidenceinterval, and (d) confidence level.
Part B: List some common confidence levels. Why not use other confidence levels? Explain.

A local university administers a comprehensive examination to the candidates for B.S. degrees in Business Administration. Five examinations are selected at random and scored. The scores are shown below.
Grades
80
90
91
62
77
I am interested in the overall performance for all candidates of a B.S. degree. The populati

Given: X ̅ = 97, sx = 16, nx = 64, Y ̅ = 90, sY = 18, nY = 81; assume the samples are independent. Construct a confidenceinterval of μX - μY according to (a) C = .95 and (b) C = .99
Here are some notes:
Rule for constructing a confidenceinterval for μX - μY when σx and σy are unknown
(X ̅- Y ̅) ±t_p s_(

If x bar =75, S = 24, and n = 36, and assuming that the population is normally distributed, construct a 95% confidenceintervalestimate of the population mean, µ.

You are constructing a 95% confidenceinterval using the information: n = 60, = 65.5, s = 2.5, and E = 0.7. What is the value of the middle of the interval?
A. 0.7
B. 2.5
C. 0.95
D. 65.5
What sample size would be needed to estimate the population mean to within one-half standard deviation with 95% confidence?