Question

If a random sample of 41 items produces x Overscript bar EndScripts = 127.4 and s = 21.6, what is the 98% confidence interval for μ? Assume x is normally distributed for the population. What is the point estimate?

Answer #1

Solution :

Given that,

t /2,df = 2.423

Margin of error = E = t/2,df * (s /n)

= 2.423 * (21.6 / 41)

Margin of error = E = 8.2

The 98% confidence interval estimate of the population mean is,

- E < < + E

127.4 - 8.2 < < 127.4 + 8.2

119.2 < < 135.6

**(119.2 , 135.6)**

Point estimate = sample mean =
= **127.4**

If a random sample of 41 items produces x = 128.4 and s = 20.6,
what is the 98% confidence interval for μ? Assume x is normally
distributed for the population. What is the point estimate?

Problem 5. 1. (a) If a random sample of 40 items produces x =
128.4 and s = 20.6, what is the 95% confidence interval for ?
Assume x is normally distributed for the population (5 points)
2. (b) Suppose the following data are selected randomly from a
population of normally distributed values. Data : 0, 10 , 20 ,5 ,15
Construct a 95% confidence interval to estimate the population
mean. (15 points)

If n=20, ¯ x (x-bar)=44, and s=15, construct a confidence
interval at a 98% confidence level. Assume the data came from a
normally distributed population.
Give your answers to one decimal place. < μ <

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standard deviation is unknown. The sample mean is x¯ = 870 and the
sample standard deviation is s = 25. Use Appendix D to find the
values of Student’s t.
(a) Construct an interval estimate of μ with 98% confidence.
(Round your answers to 3 decimal places.) The 98% confidence
interval is from to
(b) Construct an interval estimate of μ with 98% confidence,
assuming that s =...

If n=14, ¯ x x¯ (x-bar)=46, and s=8, construct a confidence
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place.

If n=18, ¯ x (x-bar)=48, and s=6, construct a confidence
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Give your answers to one decimal place.
__________ <
μ
< ________________

If n=28,
x¯(x-bar)=36,
and s=16, construct a confidence interval at a 95% confidence
level. Assume the data came from a normally distributed
population.
Give your answers to one decimal place.
__________ <
μ
< ________________

A simple random sample of size n is drawn from a population that
is normally distributed. The sample mean, overbar x, is found to
be 115, and the sample standard deviation, s, is found to be 10.
(a) Construct a 98% confidence interval about μ if the sample
size, n, is 20. (b) Construct a 98% confidence interval about μ
if the sample size, n, is 25. (c) Construct a 99% confidence
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