Question

You want to estimate the average number of times teenagers between the ages of 13 and 18 who have smoked cannabis. You take a random sample of 25 students in Raleigh and find that on average the sample smoked marijuana 128 days in the last 12 months with an SS of 180. Calculate a 95% confidence interval around the North Carolina sample. Make sure to show all four steps

Answer #1

Confidence interval for Population mean is given as below:

Confidence interval = Xbar ± t*S/sqrt(n)

From given data, we have

Xbar = 128

SS = 180

n = 25

n - 1 = 24

Variance = SS/(n - 1) = 180/24 = 7.5

S = sqrt(7.5) = 2.738613

df = n – 1 = 24

Confidence level = 95%

Critical t value = 2.0639

(by using t-table)

Confidence interval = Xbar ± t*S/sqrt(n)

Confidence interval = 128± 2.0639*2.738613/sqrt(25)

Confidence interval = 128 ± 1.1304

Lower limit = 128 - 1.1304 = 126.87

Upper limit = 128 + 1.1304 =129.13

Confidence interval = (126.87, 129.13)

QUESTION 3: As an avid golfer, you want to
estimate your average score for 18 holes of golf. Suppose you know
that the standard deviation of your score is 18.337 strokes and you
want to find a sample mean that is within 5.982 strokes of your
true average for all rounds of golf with 99% confidence. How many
rounds would you need to play to determine this?
QUESTION 4: In a climate survey, it was determined
that in a random...

You want know whether virginia adult between the ages of 22 and
50 avergae more than 12 days at the beach per year. You take a
sample of enough Virginia adults of the right age and get a p-value
pf .5505.
a. Does the evidence you collected support the claim that
Virginia adults between the ages 22 and 50 average more than 12
days at the beach per year? Why or why not?
b. Given a hyptohesis (not necessarily the...

You want to estimate the average starting salary of San Jose
graduates. You call a random sample
of 200 students who graduated in the last two years. After
collecting the data, you are about to
calculate the 95% confidence interval when you remember that
incomes
are skewed to the right. Isn’t a 95% confidence interval based on a
normal curve? Was all your
work in vain? Explain, making reference to the assumptions required
for confidence intervals to
be valid.

The owner of a local golf course wants to estimate the
difference between the average ages of males and females that play
on the golf course. He randomly samples 25 men and 28 women that
play on his course. He finds the average age of the men to be
36.105 with a standard deviation of 5.507. The average age of the
women was 48.973 with a standard deviation of 5.62. He uses this
information to calculate a 90% confidence interval...

You want to estimate the average difference between grades on a
certain math exam before students take the associated math class
and after they take the associated math class. (hopefully you do
better after taking the class, right?) you take a random sample of
5 students and get the following results.
Grade before
54
25
73
23
42
Grade after
82
76
98
43
38
question before if
that helps answer the question above : you want to estimate the...

Suppose you want to know if the average age of CEO’s at fortune
500 companies has increased in recent years. In 2010 you took a
sample of 30 CEO’s and find their average age is 47 with a sample
variance of s 2 2 = 36. In 2016 you took a sample of 25 CEO’s and
find their average age is 50 with a sample variance of S 1 2 = 25.
Assume the degrees of freedom is 42
What...

You want to esteem the average difference between grades on a
certain math exam before students take the associated math class
and after they take the math class. You take a random sample of 5
students and get the following results.
Grade Before
Grade After
54
82
25
76
73
98
23
43
42
38
A) Determine the population(s) and parameter(s) being
discussed.
B) Determine which tool will help us find what we need (one
sample z test, one sample...

Professors in the Economics Department at Western want to
determine how challenging the program was for students. Out of a
random sample of 21 students, 16 indicated that the program was
either "challenging" or "very challenging". The 95% confidence
interval estimating the proprotion of all students in the
department who thought the program was challenging is given by
which of the following?
Question 9 options:
1)
( 0.60903 , 0.91478 )
2)
( -0.57974 , 0.94407 )
3)
( 0.66896...

(15%) For Applied Management Statistics class you want to know
how college students feel
about the transportation system in
Barcelona.
What is the population in this study?
What type of sample would you use and why?
(25%) A manager of an e-commerce company would like to
determine average delivery time of the products. A sample of 25
customers is taken. The average delivery time in the sample was
four days. Suppose the delivery times are normally distributed with
a standard...

PART A) You own a small storefront retail business and are
interested in determining the average amount of money a typical
customer spends per visit to your store. You take a random sample
over the course of a month for 14 customers and find that the
average dollar amount spent per transaction per customer is
$109.477 with a standard deviation of $11.8571. Create a 90%
confidence interval for the true average spent for all customers
per transaction.
PART B) Researchers...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 1 minute ago

asked 35 minutes ago

asked 39 minutes ago

asked 55 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago