Question

ALL PROBLEM SOLVING QUESTIONS NEED TP BE SHOWN/EXPLAINED. Please and thank you.

43. For which of the following degrees of freedom is a t distribution closest to a normal distribution?

a. 10

b. 20

c. 5

d. 1000

44. In order to construct a confidence interval for the difference between two means, we are going to assume which of the followings? (Select all that apply)

a. the two populations have the same variance.

b. the populations are normally distributed.

c. each value is sampled independently from each other value.

d. the two populations have similar means

45. A researcher tries to compare grades earned on the first quiz by boys and girls. He randomly chooses 10 students from boys and 15 students from girls and calculates the confidence interval on difference between means. How many degrees of freedom will you get in this t distribution?

Answer #1

43. If the degrees of freedom in a t-distribution are greater than 30, we can assume it to be a normal distribution.

Correct option: D) 1000

44. To construct a confidence interval for the difference between two means, we will assume that the the populations have the same variance, the two populations are normally distributed and each value is sampled independently from each other value OR the samples are independent. Option D) is not a correct assumption.

Options A, B and C are correct

45. For a independent samples t-test,

df = n1 + n2 - 2

df = 10 + 15 - 2 = 25 - 2 = 23

The following results are for independent random samples taken
from two populations.
Sample 1
Sample 2
n1 = 40
n2 = 50
x1 = 32.2
x2 = 30.1
s1 = 2.6
s2 = 4.3
(a) What is the point estimate of the difference between the two
population means?
(b) What is the degrees of freedom for the t
distribution?
(c) At 95% confidence, what is the margin of error?
(d) What is the 95% confidence interval for the difference
between...

The following results are for independent random samples taken
from two populations.
Sample 1
Sample 2
n1 = 20
n2 = 30
x1 = 22.8
x2 = 20.1
s1 = 2.6
s2 = 4.6
(a)
What is the point estimate of the difference between the two
population means? (Use
x1 − x2.
)
(b)
What is the degrees of freedom for the t distribution?
(Round your answer down to the nearest integer.)
(c)
At 95% confidence, what is the margin...

The following results are for independent random samples taken
from two populations.
Sample 1
Sample 2
n1 = 20
n2 = 30
x1 = 22.5
x2 = 20.1
s1 = 2.2
s2 = 4.6
(a)
What is the point estimate of the difference between the two
population means? (Use
x1 − x2.
)
(b)
What is the degrees of freedom for the t distribution?
(Round your answer down to the nearest integer.)
(c)
At 95% confidence, what is the margin...

Consider the following results for independent random samples
taken from two populations.
Sample 1
Sample 2
n 1 = 20
n 2 = 40
x 1 = 22.1
x 2 = 20.9
s 1 = 2.4
s 2 = 4.7
What is the point estimate of the difference between the two
population means (to 1 decimal)?
What is the degrees of freedom for the t distribution
(round down your answer to nearest whole number)?
At 95% confidence, what is the...

The following results are for independent random samples taken
from two populations.
Sample 1
Sample 2
n1 = 20
n2 = 30
x1 = 22.5
x2 = 20.1
s1 = 2.9
s2 = 4.6
a) What is the point estimate of the difference between the two
population means? (Use
x1 − x2.)
b) What is the degrees of freedom for the t
distribution? (Round your answer down to the nearest integer.)
c) At 95% confidence, what is the margin of...

Consider the following results for independent random samples
taken from two populations.
Sample 1
Sample 2
n 1 = 10
n 2 = 30
x 1 = 22.5
x 2 = 20.5
s 1 = 2.5
s 2 = 4.6
What is the point estimate of the difference between the two
population means (to 1 decimal)?
What is the degrees of freedom for the t distribution
(round down your answer to nearest whole number)?
At 95% confidence, what is the...

Consider the following results for independent random samples
taken from two populations.
Sample 1
Sample 2
n 1 = 10
n 2 = 30
x 1 = 22.5
x 2 = 20.5
s 1 = 2.5
s 2 = 4.6
What is the point estimate of the difference between the two
population means (to 1 decimal)?
What is the degrees of freedom for the t distribution
(round down your answer to nearest whole number)?
At 95% confidence, what is the...

*Answer all questions using R-Script*
Question 1
Using the built in CO2 data frame, which contains data from an
experiment on the cold tolerance of Echinochloa crus-galli; find
the following.
a) Assign the uptake column in the
dataframe to an object called "x"
b) Calculate the range of x
c) Calculate the 28th percentile of
x
d) Calculate the sample median of
x
e) Calculate the sample mean of x and
assign it to an object called "xbar"
f) Calculate...

The Nielsen Company is a global information and media company
and one of the leading suppliers of media information. In their
state-of-the-media report, they announced that U.S. cell phone
subscribers average 5.4 hours per month watching videos on their
phones. We decide to construct a 95% confidence interval for the
average time (hours per month) spent watching videos on cell phones
among U.S. college students. We draw the following SRS of size 8
from this population.
11.8 2.7 3.0 6.1 4.8 9.8 11.2 7.7
We want to...

7.
(07.02 MC)
Oscar, a yoga instructor at Yoga for You, is interested in
comparing levels of physical fitness of students attending a nearby
high school and those attending a local community college. He
selects a random sample of 210 students from the high school. The
mean and standard deviation of their fitness scores are 82 and 14,
respectively. He also selects a random sample of 210 students from
the local community college. The mean and standard deviation of
their...

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