Question

The monthly untily bills in a city are normally distributed
with a mean of $100 with standard deviation of $15. find the
probability that a randomly selected utility bill is less than $65?
between $80 and $90? and more than $100?

Answer #1

Solution,

Given that ,

mean = = 100

standard deviation = =15

1) P(x < 65 ) = P[(x - ) / < ( 65 - 100) / 15 ]

= P(z < -2.33 )

Using z table

= 0.0099

2) P( 80 < x < 90 ) = P[( 80 - 100)/ 15 ) < (x - ) / < ( 90 - 100 ) / 15 ) ]

= P( -1.33 < z < -0.67 )

= P(z < -0.67 ) - P(z < - 1.33 )

Using z table

= 0.2514 - 0.0918

= 0.1596

3) P(x > 100 ) = 1 - P(x < 100 )

= 1 - P[(x - ) / < ( 100 - 100 ) / 15 ]

= 1 - P(z < 0 )

Using z table

= 1 - 0.5000

= 0.5000

The monthly utility bills in a city are normally distributed,
with a mean of $100 and a standard deviation of $16. Find the
probability that a randomly selected utility bill is (a) less than
$67, (b) between $80 and $100, and (c) more than $110.
(a) The probability that a randomly selected utility bill is
less than $67 is nothing. (Round to four decimal places as
needed.)
(b) The probability that a randomly selected utility bill is
between $80 and...

17 (CO 3) A survey indicates that shoppers spend an average of
22 minutes with a standard deviation of 16 minutes in your store
and that these times are normally distributed. Find the probability
that a randomly selected shopper will spend less than 20 minutes in
the store
18(CO 3) The monthly utility bills in a city are normally
distributed with a mean of $121 and a standard deviation of $23.
Find the probability that a randomly selected utility bill...

Assume that adults have IQ scores that are normally distributed
with a mean of 100 and a standard deviation of 15. For a randomly
selected adult, find the probability. Round scores to nearest whole
number.
1.) Prob. of IQ less than 85
2.)Prob. of IQ greater than 70
3.) Prob. of randomly selected adult having IQ between 90 and
110.

Electricity bills in a certain city have mean $87.57. Assume the
bills are normally distributed with standard deviation $14.97. A
sample of 80 bills was selected for an adult. Find the 53
percentile for the sample mean. Write only a number as your answer.
Round to two decimal places (for example: 42.81). Do not write any
units.

7. IQ scores are normally distributed with a mean of 100 and a
standard deviation of 15 points.
a. Find the probability that a randomly selected person has an
IQ less than 115.
b. Find the probability that a randomly selected person has an
IQ above 60.
c. Find the 80th percentile for IQ scores.
d. Find the probability that 20 randomly selected person has an
IQ less than 110.
e. What percentage of people have IQ scores between 60...

According to a report by Scarborough
Research, the average monthly household cellular phone bill is $73.
Suppose local monthly household cell phone bills are normally
distributed with a standard deviation of $22.
What is the probability that a randomly selected monthly cell
phone bill is less than $95?
What is the probability that a randomly selected monthly cell
phone bill is between $62 and $84?
According to a report by Scarborough
Research, the average monthly household cellular phone bill is...

The mean of a normally distributed data set is 112, and the
standard deviation is 18.
a) Use the Empirical Rule to find the probability
that a randomly-selected data value is greater than 130.
b) Use the Empirical Rule to find the probability
that a randomly-selected data value is greater than 148.
A psychologist wants to estimate the proportion of people in a
population with IQ scores between 85 and 130. The IQ scores of this
population are normally distributed...

In
a certain city, heights of young men are distributed normally with
a mean of 173 centimeters and a standard deviation of 30
centimeters.
A. Find the probability that a randomly selected man from this
city is taller than 190 centimeters.
B. Find the probability that the mean height of 16 randomly
selected men from this city is taller than 190 centimeters.

For question 10, assume that adults have IQ scores that are
normally distributed with a mean of 100 and a standard deviation of
15. Find the probability that a randomly selected adult has an IQ
of the following: 10. Find the area under the standard normal curve
for the following: • Less than 115. • Greater than 131.5 • Between
90 and 110 • Between 110 and 120

For the following, consider that IQ scores are normally
distributed with a mean of 100 and a standard deviation of 15.
Find the probability that a person has an IQ below 60
Find the probability that a randomly selected person has an IQ
between 60 and 85
Find the probability that a randomly selected person has an IQ
above 118.
Find the IQ score that cuts off the lower 25% of the population
from the upper 75%.
Find the probability...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 22 minutes ago

asked 24 minutes ago

asked 29 minutes ago

asked 56 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