Question

The students collect a random sample of 45 students. The mean of the sample is 12.1 units. The sample has a standard deviation of 1.5 units.

What is the 95% confidence interval for the average number of units that students in their college are enrolled in? Assume that the distribution of individual student enrollment units at this college is approximately normal. (round to 2 decimal places)

ANSWER: (_____, _____)

Answer #1

1. A questionnaire of spending
habits was given to a random sample of college students. Each
student was asked to record and report the amount of money they
spent on books and school supplies in a semester. The amount of
money spent on books and school supplies is said to follow normal
distribution. The sample of 85 students resulted in an average of
$850.
a) What are the simple conditions
necessary for the confidence interval to be valid?
b) Find...

2. A research takes a simple random sample of 400 students out
of 10,000 students at a university. On the average, there are .48
cats per sample student, and the SD is .15. Say where each of the
following statement is true or false, explain.
a. The .48 is .15 or so off the average number of cats per
student in the university.
b. A 95% confidence interval for the average number of cats per
student in the sample is...

2. A research takes a simple random sample of 400 students out
of 10,000 students at a university. On the average, there are .48
cats per sample student, and the SD is .15. Say where each of the
following statement is true or false, explain. a. The .48 is .15 or
so off the average number of cats per student in the university. b.
A 95% confidence interval for the average number of cats per
student in the sample 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.

In order to determine how many hours per week freshmen college
students watch television, a random sample of 25 students was
selected. It was determined that the students in the sample spent
an average of 19.5 hours with a sample standard deviation of 3.9
hours watching TV per week. Please answer the following questions:
(a) Provide a 95% confidence interval estimate for the average
number of hours that all college freshmen spend watching TV per
week. (b) Assume that a...

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...

A college admissions director wishes to estimate the mean age of
all students currently enrolled. In a random sample of 19 students,
the mean age is found to be 23.7 years. From past studies, the ages
of enrolled students are normally distributed with a standard
deviation of 10.4 years. Construct a 90% confidence interval for
the mean age of all students currently enrolled.
1. The critical value:
2. The standard deviation of the sample mean:
3. The margin of error...

A random sample of 50 students has a mean GPA of 2.55. It is
known that the population standard deviation for the GPA of all
students is 1.1. Use this information to complete the
following:
a) Does the information above provide an estimate of a
population mean or a population proportion?
b) Provide a point estimate for the population mean GPA of all
students.
c) Construct and interpret a 95% confidence interval for the
parameter you selected in part (a)....

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...

From a random sample of 16 bags of chips, sample mean weight is
500 grams and sample standard deviation is 3 grams. Assume that the
population distribution is approximately normal. Answer the
following questions 1 and 2.
1. Construct a 95% confidence interval to estimate the
population mean weight. (i) State the assumptions, (ii) show your
work and (iii) interpret the result in context of the problem.
2. Suppose that you decide to collect a bigger sample
to be more accurate....

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