Question

1. Assume that we want to construct a confidence interval. Do one of the following, as appropriate: (a) find the critical value t Subscript alpha divided by 2, (b) find the critical value z Subscript alpha divided by 2, or (c) state that neither the normal distribution nor the t distribution applies. Here are summary statistics for randomly selected weights of newborn girls: n=181, x= 33.7 hg, s= 7.6 hg. The confidence level is 99%.

a. tα/2e=

B. za/2 =

c. Neither the normal distribution nor the t distribution applies.

2. Here are summary statistics for randomly selected weights of newborn girls: n=157, x =31.2 hg, s=6.9 hg. Construct a confidence interval estimate of the mean. Use a 90% confidence level. Are these results very different from the confidence interval 29.6 hg <μ<32.0 hg with only 15 sample values, x =30.8hg, and s=2.7 hg?

-----hg<μ< ---- Round to one decimal place

3. A clinical trial was conducted to test the effectiveness of a drug for treating insomnia in older subjects. Before treatment, 15 subjects had a mean wake time of 104.0 min. After treatment, the 15 subjects had a mean wake time of 76.4 min and a standard deviation of 24.8 min. Assume that the 15 sample values appear to be from a normally distributed population and construct a 99% confidence interval estimate of the mean wake time for a population with drug treatments. What does the result suggest about the mean wake time of 104.0 min before the treatment? Does the drug appear to be effective?

-----min<μ<-----min Round to one decimal place

Answer #1

1)

2) At 90% confidence level, the critical value is
z_{0.05} = 1.645

The 90% confidence interval is

= 30.29, 32.11

= 30.3, 32.1

No, the results are not very different from the confidence interval 29.6 < < 32.0.

3) df = 15 - 1 = 14

At 99% confidence level, the critical value is t^{*} =
2.977

The 99% confidence interval is

Yes, the drug appear to be effective, since 104 does not lie in the confidence interval.

Assume that we want to construct a confidence interval. Do one
of the following, as appropriate: (a) find the critical value t
Subscript alpha divided by 2, (b) find the critical value z
Subscript alpha divided by 2, or (c) state that neither the
normal distribution nor the t distribution applies. Here are
summary statistics for randomly selected weights of newborn girls:
nequals290, x overbarequals31.9 hg, sequals6.1 hg. The confidence
level is 90%. Please help!

Assume that we want to construct a confidence interval. Do one
of the following, as appropriate: (a) find the critical value t
Subscript alpha divided by 2tα/2, (b) find the critical value z
Subscript alpha divided by 2zα/2, or (c) state that neither the
normal distribution nor the t distribution applies. Here are
summary statistics for randomly selected weights of newborn girls:
n=289289, x overbarxequals=32.632.6 hg, s=7.67.6 hg. The
confidence level is 95%.

Assume that we want to construct a confidence interval. Do one
of the following, as appropriate: (a) find the critical value t
Subscript alpha divided by 2, (b) find the critical value z
Subscript alpha divided by 2, or (c) state that neither the
normal distribution nor the t distribution applies. Here are
summary statistics for randomly selected weights of newborn girls:
nequals224, x overbarequals31.4 hg, sequals6.5 hg. The confidence
level is 99%. Select the correct choice below and, if...

Assume that we want to construct a confidence interval. Do one
of the following, as appropriate: (a) find the critical value t
Subscript alpha divided by 2tα/2, (b) find the critical value z
Subscript alpha divided by 2zα/2, or (c) state that neither the
normal distribution nor the t distribution applies. Here are
summary statistics for randomly selected weights of newborn girls:
nequals=239239, x overbarxequals=33.433.4 hg, sequals=7.97.9 hg.
The confidence level is 9595%.
Select the correct choice below and, if...

Assume that we want to construct a confidence interval. Do one
of the following, as appropriate: (a) find the critical value t
Subscript alpha divided by 2, (b) find the critical value z
Subscript alpha divided by 2, or (c) state that neither the
normal distribution nor the t distribution applies. Here are
summary statistics for randomly selected weights of newborn girls:
n = 156, x overbar = 33.3 hg, s = 7.9 hg. The confidence level is
95%.
Select...

Assume that we want to construct a confidence interval. Do one
of the following, as appropriate: (a) find the critical value t
Subscript alpha divided by 2tα/2 (b) find the critical value z
Subscript alpha divided by 2zα/2, or (c) state that neither the
normal distribution nor the t distribution applies. The confidence
level is 99%, sigmaσequals=3210 thousand dollars, and the
histogram of 62 player salaries (in thousands of dollars) of
football players on a team is as shown.
Select...

A clinical trial was conducted to test the effectiveness of a
drug for treating insomnia in older subjects. Before treatment, 16
subjects had a mean wake time of 104.0 min. After treatment, the
16 subjects had a mean wake time of 98.2 min and a standard
deviation of 22.8 min. Assume that the 16 sample values appear to
be from a normally distributed population and construct a 95%
confidence interval estimate of the mean wake time for a population
with...

A clinical trial was conducted to test the effectiveness of a
drug for treating insomnia in older subjects. Before treatment,21
subjects had a mean wake time of 104.0min. After treatment, the 21
subjects had a mean wake time of 80.2 min and a standard deviation
of 24.7 min. Assume that the 21 sample values appear to be from a
normally distributed population and construct a 95% confidence
interval estimate of the mean wake time for a population with drug
treatments....

A clinical trial was conducted to test the effectiveness of a
drug for treating insomnia in older subjects. Before treatment, 15
subjects had a mean wake time of 105.0 min. After treatment, the
15 subjects had a mean wake time of 101.6 min and a standard
deviation of 21.5 min. Assume that the 15 sample values appear to
be from a normally distributed population and construct a 90%
confidence interval estimate of the mean wake time for a population
with...

A clinical trial was conducted to test the effectiveness of a
drug for treating insomnia in older subjects. Before treatment, 15
subjects had a mean wake time of 102.0 min. After treatment, the
15 subjects had a mean wake time of 96.3 min and a standard
deviation of 23.5 min. Assume that the 15 sample values appear to
be from a normally distributed population and construct a 95%
confidence interval estimate of the mean wake time for a population
with...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 1 minute ago

asked 7 minutes ago

asked 8 minutes ago

asked 12 minutes ago

asked 12 minutes ago

asked 17 minutes ago

asked 22 minutes ago

asked 42 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago