Question

Suppose that a study shows that an electric bike is driven 23,500 km/year on average and has a standard deviation of 3900 km. Assume that the measurements’ distribution is approximately normal.

a) Calculate the 3rd quartile.

b) Solve for the probability that a randomly selected electric bike is driven between 10,000 and 20,000 km per year.

Answer #1

It is claimed that automobiles are driven on
average more than 20,000 kilometers per year. To test
this claim, 100 randomly selected automobile owners
are asked to keep a record of the kilometers they travel.
Would you agree with this claim if the random sample
showed an average of 23,500 kilometers and a standard
deviation of 3900 kilometers? Use a P-value in your
conclusion.
but construct a 99% confidence interval

A random sample of 200 automobile owners in a region shows that
an automobile is driven on average 22 comma 500 kilometers per year
with a standard deviation of 3700 kilometers. Assume the
distribution of measurements to be approximately normal. (a)
Construct a 90% confidence interval for the average number of
kilometers an automobile is driven annually in the region. (b)
What can we assert with 90% confidence about the possible size of
our error if we estimate the average...

The average teacher's salary in Connecticut (ranked first among
states) is $57,337. Suppose that the distribution of salaries is
normal with a standard deviation of $7500.What is the probability
that a randomly selected teacher makes less than $49,000 per
year?

The average yearly salary of RN’s is $70,000. If the
distribution of salaries is
approximately normal with a standard deviation of $5,000,what is
the probability that
a randomly selected RN makes:
Between $60,000 and $70,000 a year.
More than $70,000 a year.

The average income tax refund for the 2009 tax year was $2847.
Assume the refund per person follows the normal probability
distribution with a standard deviation of $906. Complete parts a
through d below. a. What is the probability that a randomly
selected tax return refund will be more than $2100? nothing
(Round to four decimal places as needed.) b. What is the
probability that a randomly selected tax return refund will be
between $1600 and $3000? nothing (Round to...

An imaginary study states that Americans watch an average of
1400 hours of streaming videos each year. If the standard deviation
of the distribution is 221 hours, find the probability that the
mean of a randomly selected sample of 50 Americans will be between
1380 and 1430 hours.

The average teacher’s salary is $45,000. Assume a normal
distribution with standard deviation equal to $10,000. a) What is
the probability that a randomly selected teacher makes greater than
$65,000 a year? b) If we sample 100 teachers’ salaries, what is the
probability that the sample mean will be greater than $65,000?

A gasoline tank for a certain car is designed to hold 15 gallons
of gas. Suppose that the actual capacity for a randomly selected
tank has a distribution that is approximately normal with the mean
of 15 gallons and a standard deviation of 0.15 gallons. If 4 tanks
are randomly selected, what is the probability that their average
capacity will be between 14.75 and 16.10 gallons?
Please show work and explain, thank you.

[5] 3. The
average teacher’s salary is $45,000. Assume a normal distribution
with standard
deviation equal to $10,000.
What is the probability that a randomly selected teacher makes
greater than $65,000 a year?
If we sample 100 teachers’ salaries, what is the probability
that the sample mean will be greater than $65,000?

Suppose that the average number of Facebook friends users have
is normally distributed with a mean of 113 and a standard deviation
of about 43. Assume forty individuals are randomly chosen. Answer
the following questions. Round all answers to 4 decimal places
where possible.
What is the distribution of ¯xx¯? ¯xx¯ ~ N(,)
For the group of 40, find the probability that the average
number of friends is more than 119.
Find the first quartile for the average number of...

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