Question

Suppose that a simple random sample of 200 college students had the average GPA x =3.05 with a standard deviation s =0.44. (a) Construct a 98% conﬁdence interval for the mean GPA in the student population.

Answer #1

Ages of students: A simple random sample of 100
U.S. college students had a mean age of 22.68 years. Assume the
population standard deviation is σ = 4.74 years. Construct
a 99% confidence interval for the mean age of U.S. college
students.
The answer I posted my instructor says it is wrong. I came up
with 21.45 to 23.91 a 99% confidence interval for the mean of the
U.S college students
She said the z procedures are needed.
Thanks.

9. (19) A random
sample of 64 UPW college students shows that the sample mean GPA is
2.82 with a standard deviation of 0.45.
(a) Construct a 90%
Confidence Interval for the mean GPA of all UPW students.
(b) If we want to be
95% confident, and we want to control the maximum error of
estimation to 0.1, how many more students should be added into the
given sample?
(c) Would you
conclude that the mean GPA in UPW is...

A random sample of 200 students in a statistics class revealed a
mean test score of 78. If the standard deviation of the population
was 5.5, ﬁnd the 90% conﬁdence interval for the unknown population
mean test score.

In a sample of n=3,600 students, the average GPA was x⎯⎯=3.5
with a sample variance of s2=0.25. Calculate the 98% confidence
interval for the population GPA μHolding everything constant, what
would be the lower limit of the 90% confidence interval for the
population mean? (round to two digits)
Question 7 options:
3.48
3.49
3.51
3.52

Determine the sample size needed to construct a 90% confidence
interval to estimate the average GPA for the student population at
a college with a margin of error equal to 0.4. Assume the standard
deviation of the GPA for the student population is 3.5

College tuition: A simple random sample of 35
colleges and universities in the United States has a mean tuition
of $17,800 with a standard deviation of $10,400. Construct a 98%
confidence interval for the mean tuition for all colleges and
universities in the United States.
A 98% confidence interval for the mean tuition for all colleges
and universities is x<u<x

Determine the sample size needed to construct a 90% confidence
interval to estimate the average GPA for the student population at
a college with a margin of error equal to 0.5. Assume the standard
deviation of the GPA for the student population is 3.0. The sample
size needed is ?

The heights of a random sample of 50 college students showed a
mean of 174.5 centimeters and a standard deviation of 6.9
centimeters. Construct a 98% confidence interval for:
a) the mean height
b) the standard deviation of heights of all college students.
State assumptions.

The heights of a random sample of 50 college students showed a
mean of 174.5 centimeters and a standard deviation of 6.9
centimeters.
Construct a 98% confidence interval for:
a) the mean height
b) the standard deviation of heights of all college students.
State assumptions.

A random sample of 25 college students attending the RWU Spring
Concert showed that they had an average amount of $15.00 cash in
their pockets. This same sample data had a sample standard
deviation of $2.50.
a. (3 pts.) What is the point estimate for the population mean µ,
amount of cash in the pockets of a RWU student?
b. (4 pts.) Find the 95% confidence interval for the population
mean µ, amount of cash in the pockets of a...

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