Question

A researcher wished to compare the average amount of time spent in extracurricular activities by high school students in a suburban school district with that in a school district of a large city. The researcher obtained a simple random sample of 60 high school students in a large suburban school district and found the mean time spent in extracurricular activities per week to be six hours with a standard deviation of three hours. The researcher also obtained an independent simple random sample of 40 high school students in a large city school district and found the mean time spent in extracurricular activities per week to be four hours with a standard deviation of two hours. Let 1 and 2 represent the mean amount of time spent in extracurricular activities per week by the populations of all high school students in the suburban and city school districts, respectively. Assume two-sample t procedures are safe to use? 5. What is a 95% confidence interval for 1 – 2? (Assume that the variances are not equal for the t-statistic.) If we assume that the variances are different for the two groups, what would be the number of degrees of freedom for the two-sample t procedures?

Answer #1

A researcher was interested in comparing the amount of time
spent watching television by women and by men. Independent simple
random samples of 14 women and 17 men were selected, and each
person was asked how many hours he or she had watched television
during the previous week.
The summary statistics are as follows:
Women Men
_
Sample mean 11.9
hrs 16.9 hrs
Sample SD 4.1
hrs 4.8 hrs
Sample
size
14
17
Use this data and a 0.05 significance...

A researcher wished to compare the average daily hotel room
rates between San Francisco and Los Angeles. The researcher
obtained an SRS of 15 hotels in downtown San Francisco and found
the sample mean x1=$156 , with a standard deviation s1= $15 . The
researcher also obtained an independent SRS of 10 hotels in
downtown Los Angeles and found the sample mean x2= $143, with a
standard deviation s2=$10.
Let 1 and 2 represent the mean cost of the populations...

A researcher was interested in comparing the amount of time
spent watching television
by women and by men. Independent simple random samples of 14 women
and 17 men
were selected, and each person was asked how many hours he or she
had watched
television during the previous week. The summary statistics are as
follows:
Women Men .
Sample
Mean 12.9 16.4
Sample
SD 4.0 4.2
Sample
Size 14 17
This sample data is then used to test the claim that the mean time
spent watching
television by women...

In a survey of collage students, it was found that the amount of
time spent on reading books per week was normally distributed with
a mean of 32 minutes. Assume the distribution of weekly reading
time follows the normal distribution with a population standard
deviation of 2 minutes. Suppose we select a sample of 20 high
school students.
1) What is the standard error of the mean time?
2)What percent of the sample means will be greater than 32.50
minutes?
3)What...

Full-time college students report spending a mean of 28 hours
per week on academic activities, both inside and outside the
classroom. Assume the standard deviation of time spent on academic
activities is 6 hours. Complete parts (a) through (d) below.
If you select a random sample of 25 full-time college
students, what is the probability that the mean time spent on
academic activities is at least 27 hours per week?

Today, full-time college students report spending a mean of 27
hours per week on academic activities, both inside and outside the
classroom. (Source: “A Challenge to Col- lege Students for 2013:
Don’t Waste Your 6,570,” Huffington Post, January 29, 2013,
huff.to/13dNtuT.) Assume the standard devia- tion of time spent on
academic activities is 4 hours. If you select a random sample of 16
full-time college students,
PLEASE USE NORMDIST AND NORMINV IN EXCEL
what is the probability that the mean...

Today, full-time college students report spending a mean of 27
hours per week on academic activities, both inside and outside the
classroom. (Source: “A Challenge to Col- lege Students for 2013:
Don’t Waste Your 6,570,” Huffington Post, January 29, 2013,
huff.to/13dNtuT.) Assume the standard devia- tion of time spent on
academic activities is 4 hours. If you select a random sample of 16
full-time college students,
PLEASE USE NORMDIST AND NORMINV IN EXCEL
what is the probability that the mean...

A researcher was interested in comparing the amount of time (in
hours) spent watching television by women and by men. Independent
simple random samples of 14 women and 17 men were selected, and
each person was asked how many hours he or she had watched
television during the previous week. The summary statistics are as
follows.
Use a 0.05 significance level to test the claim that the mean
amount of time spent watching television by women is smaller than
the...

Full-time college students report spending a mean of 25hours per
week on academic? activities, both inside and outside the
classroom. Assume the standard deviation of time spent on academic
activities is 4 hours. Complete parts? (a) through? (d) below.
a. If you select a random sample of 25 ?full-time college?
students, what is the probability that the mean time spent on
academic activities is at least 24 hours per? week?
?(Round to four decimal places as? needed.)
b. If you...

Today, full time college students report spending a mean of 27
hours per week on academic activities, both inside and outside of
the classroom. Assume the standard deviation of time spent on
academic activities is 4 hours. If you select a random sample of 50
full-time college students:
A. Describe the shape of the sampling distribution. How do you
know it is this shape?
B. Find the mean and standard deviation for the distribution of
the sample mean (x bar)...

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