Question
In: Statistics and Probability
2. You randomly select 16 cars of the same model that were sold at a car...
2. You randomly select 16 cars of the same model that were sold at a car dealership and determine the number of days each car sat on the dealership’s lot before it was sold. The sample mean is 9.15 days, with a sample standard deviation of 1.6 days. Construct a 95% confidence interval for the population mean number of days the car model sits on the dealership’s lot. (10 p)
(Round off final answers to two decimal places, if appropriate. Do not round off numbers taken directly from tables).
3. A researcher collected data from a random sample of 25 high school freshmen and found the mean of the sample to be 85.40 on the Test of Critical Thinking (TCT). She also calculated the standard deviation from the sample and discovered the value was 12.30. The average score on the Test of Critical Thinking for all high school seniors in a large school district is 90.00. The researcher wants to know if the mean TCT of the 25 high school freshmen in the random sample is different from the population’s (i.e., highschool seniors) TCT mean.
(Round off final answers to two decimal places, if appropriate. Do not round off numbers taken directly from tables).
e. What decision should be made about the null hypothesis? In other words, should you reject or retain the null hypothesis? (10p)
g. Provide a brief conclusion regarding your findings. Use your power point lecture slides for writing out the interpretation of your results. (10p)
Solutions
orchestra answered 1 year agoRelated Solutions
You randomly select 36 cars of the same model that were sold at a car dealership...
You randomly select 36 cars of the same model that were sold at
a car dealership and determine the number of days each car sat on
the dealership’s lot before it was sold. The sample mean is 9.75
days, with a sample standard deviation of 2.39 days. Construct a
99% confidence interval for the population mean number of days the
car model sits on the dealership’s lot
You randomly select 20 cars of the same model that were sold at a car dealership...
You randomly select 20 cars of the same model that were sold at
a car dealership and determine the number of days each car sat on
the dealership’s lot before it was sold. The sample mean is 9.75
days, with the sample standard deviation of 2.39 days. Construct a
99% confidence interval for the population mean number of days the
car model sits on the dealership’s lot. Assume the days on the lot
is normally distributed.
Suppose that you own a car dealership and purchase (randomly select) 10 cars of a certain...
Suppose that you own a car dealership and purchase (randomly
select) 10 cars of a certain make from a production run of 200
cars. Of the 200 cars, 160 are destined to last at least five years
without needing a major repair.
Using the hypergeometric distribution what is the probability
that at least 6 of your 10 cars will last at least five years
without needing a major repair.
Scenario 2: Car crashes ~ Randomly selected deaths from car crashed were obtained and the results...
Scenario 2: Car crashes ~ Randomly selected
deaths from car crashed were obtained and the results are shown in
the table below:
Day
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Fatalities
132
108
95
99
115
132
138
State officials wonder if car crash fatalities occur with
unequal frequency on different days of the week. They represent
this research question in terms of two competing hypotheses:
H0: Car crashes occur with equal frequency throughout the week
and that any uneven...
17) Not everyone pays the same price for the same model of a car. For a...
17) Not everyone pays the same price for the same model of a
car. For a particular new car the mean price is $18,750 with a
standard deviation of $690. ROUND VALUES CORRECTLY TO
DOLLAR.
a) Make a sketch of the normal distribution, labeling the center
and ± 1, 2, 3SD intervals with the values.
b) If a car is picked at random, what is the probability that
the car price is between $17,800 and $19,100?
c) A car in...
One of the cars sold by Walt's car dealership is a very popular subcompact car called...
One of the cars sold by Walt's car dealership is a very popular
subcompact car called the Rhino. The final sale price of the basic
model of this car varies from customer to customer depending on the
negotiating skills and persistence of the customer. Assume that
these sale prices of this car are normally distributed with a mean
of $19900 and a standard deviation of $360. Round your answers to 2
decimal places.
a. Dolores paid $19525 for her Rhino....
You randomly select 22 student cars and find they have a mean age of 8 years...
You randomly select 22 student cars and find they have
a mean age of 8 years and a standard deviation of 3.4 years. You
also randomly select 28 faculty cars and find they have a mean age
of 5.3 years and a standard deviation of 3.7 years.
Use a 0.01 significance level to test the claim that
student cars are older than faculty cars.
(a) test statistic
(b) the p-value
You randomly select 22 student cars and find they have a mean age of 8 years...
You randomly select 22 student cars and find they have
a mean age of 8 years and a standard deviation of 3.4 years. You
also randomly select 28 faculty cars and find they have a mean age
of 5.3 years and a standard deviation of 3.7 years.
Use a 0.01 significance level to test the claim that
student cars are older than faculty cars.
(a) test statistic
(b) the p-value
You are a car thief. You steal late-model cars in a major U.S. city and drive...
You are a car thief. You steal late-model cars in a major U.S.
city and drive them across the border to sell them for an average
price of $10,000. You are enrolled in Ms. Smith’s managerial
accounting class and you want to know if crime, indeed, does pay.
So you calculate your costs thus:
~ on average, you drive 2,000 miles from start to destination.
Your gas cost over the past year has averaged $3.00 a gallon, and
most of...
1. You randomly select 36 restaurants and measure the temperature of coffee sold at each. The...
1. You randomly select 36 restaurants and measure the
temperature of coffee sold at each. The sample mean temperature is
162.0°F. Temperatures historically have had a population standard
deviation of 10.0°F. Which of the following intervals is the
correct 95% confidence interval for the true mean? (T interval or Z
interval)
2. If all other quantities remain the same, how does the
indicated change affect the width of a confidence interval?
Decrease the level of confidence from 95% to 90%?
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