Question 1

The standardized normal quartile value Oi is the z value that gives an area of i/(n - 1)to its right under the normal curve.

Accepted Answer

A) True 
 B)False

Question 2

The time between breakdowns of an alarm system is exponentially distributed with mean 10 days.What is the probability that there are no breakdowns on a given day?

Accepted Answer

A) .9048 
B) .3679 
C) .0952 
D) 0.000

Question 3

The specific shape of each normal distribution is determined by its ____________ and ____________.

Accepted Answer

A) Mean,standard deviation 
B) Median,standard deviation 
C) Mean,variance 
D) Median,variance

Question 4

The random variable x has a uniform distribution when x lies between the values of 4 and 10.When x = 10,what is the value of f(x)?

Accepted Answer

A) 0 
B) 1 
C) 1/6 
D) 1/14

Question 5

Suppose that the waiting time for a license plate renewal at a local office of a state motor vehicle department has been found to be normally distributed with a mean of 30 minutes and a standard deviation of 8 minutes.What is the probability that a randomly selected individual will have a waiting time of no more than 22 minutes

Accepted Answer

A) .1587 
B) .9977 
C) .8413 
D) .0023

Question 6

Given that the length an athlete throws a hammer is a normal random variable with mean 50 feet and standard deviation 5 feet,what is the probability he throws it between 50 feet and 60 feet?

Accepted Answer

A) .9972 
B) .5000 
C) .9544 
D) .4772

Question 7

The population of lengths of aluminum-coated steel sheets is normally distributed with a mean of 30.05 inches and a standard deviation of 0.2 inches.What is the probability that a sheet selected at random will be less than 29.75 inches long?

Accepted Answer

A) .8944 
B) .1056 
C) .9332 
D) .0668

Question 8

The actual weight of hamburger patties is an example of a continuous random variable.

Accepted Answer

A) True 
 B)False

Question 9

When a ____________ probability distribution is used to approximate a ____________ probability distribution,we must make a ____________ correction.

Accepted Answer

A) Continuous,discrete,continuity 
B) Discrete,continuous,continuity 
C) Continuous,discrete,finite population 
D) None of these

Question 10

An aptitude test has a mean score of 80 and a standard deviation of 5.The population of scores is normally distributed.What raw score corresponds to the 70th percentile?

Accepted Answer

A) 77.4 
B) 83.5 
C) 82.6 
D) 76.5

Question 11

If the mileage per gallon for a car is normally distributed,32 mpg has a z score of 1.2,and 24 mpg has a z score of -.4,what is the mean mpg of the distribution?

Accepted Answer

A) 28 
B) 26 
C) 30 
D) 38

Question 12

An apple juice producer buys all his apples from a conglomerate of apple growers in one northwestern state.The amount of juice squeezed from each of these apples is approximately normally distributed with a mean of 2.25 ounces and a standard deviation of 0.15 ounce.What is the probability that a randomly selected apple will contain between 2.00 and 3.00 ounces?

Accepted Answer

A) .0475 
B) .4525 
C) .9525 
D) .9554

Question 13

While conducting experiments,a marine biologist selects water depths from a uniformly distributed collection that vary between 2.00 m and 7.00 m.What is the expected value of the water depth?

Accepted Answer

A) 1.4 
B) 2.6 
C) 2.5 
D) 4.5

Question 14

The cashier service time at the local branch of the Rivertown bank has an exponential distribution with a mean of 2.5 minutes.What is the probability that the service time exceeds 3 minutes?

Accepted Answer

A) .3012 
B) .6988 
C) .4346 
D) .5654 
E) .0821

Question 15

The mean of a standard normal distribution is always equal to 1.

Accepted Answer

A) True 
 B)False

Question 16

Suppose that the times required for a cable company to fix cable problems in its customers' homes are uniformly distributed between 40 minutes and 65 minutes.What is the probability that a randomly selected cable repair visit falls within 2 standard deviations of the mean?

Accepted Answer

A) 0.75 
B) 1.00 
C) 0.58 
D) 0.86

Question 17

The binomial random variable x consists of n = 60 trials and has the probability of failure q = 0.4.Using the normal approximation,compute the probability of 19 successes.

Accepted Answer

The answer of The binomial random variable x consists of...

Question 18

Find z when the area to the left of z is .05.

Accepted Answer

A) 1.645 
B) 1.00 
C) -1.645 
D) -1.96

Question 19

A standard normal distribution has a mean of ____________ and standard deviation of ____________.

Accepted Answer

A) Zero,zero 
B) Zero,one 
C) One,one 
D) One,zero

Question 20

Consider a normal population with a mean of 10 and a variance of 4.Find P(X > 7).

Accepted Answer

A) .0668 
B) .9332 
C) .8413 
D) .1587

Exam 6: Continuous Random Variables

The standardized normal quartile value O_i is the z value that gives an area of i/(n - 1)to its right under the normal curve.

The time between breakdowns of an alarm system is exponentially distributed with mean 10 days.What is the probability that there are no breakdowns on a given day?

The specific shape of each normal distribution is determined by its and .

The random variable x has a uniform distribution when x lies between the values of 4 and 10.When x = 10,what is the value of f(x) ?

Given that the length an athlete throws a hammer is a normal random variable with mean 50 feet and standard deviation 5 feet,what is the probability he throws it between 50 feet and 60 feet?

The population of lengths of aluminum-coated steel sheets is normally distributed with a mean of 30.05 inches and a standard deviation of 0.2 inches.What is the probability that a sheet selected at random will be less than 29.75 inches long?

The actual weight of hamburger patties is an example of a continuous random variable.

When a probability distribution is used to approximate a probability distribution,we must make a correction.

An aptitude test has a mean score of 80 and a standard deviation of 5.The population of scores is normally distributed.What raw score corresponds to the 70^th percentile?

If the mileage per gallon for a car is normally distributed,32 mpg has a z score of 1.2,and 24 mpg has a z score of -.4,what is the mean mpg of the distribution?

While conducting experiments,a marine biologist selects water depths from a uniformly distributed collection that vary between 2.00 m and 7.00 m.What is the expected value of the water depth?

The cashier service time at the local branch of the Rivertown bank has an exponential distribution with a mean of 2.5 minutes.What is the probability that the service time exceeds 3 minutes?

The mean of a standard normal distribution is always equal to 1.

Suppose that the times required for a cable company to fix cable problems in its customers' homes are uniformly distributed between 40 minutes and 65 minutes.What is the probability that a randomly selected cable repair visit falls within 2 standard deviations of the mean?

The binomial random variable x consists of n = 60 trials and has the probability of failure q = 0.4.Using the normal approximation,compute the probability of 19 successes.

Find z when the area to the left of z is .05.

A standard normal distribution has a mean of and standard deviation of .

Consider a normal population with a mean of 10 and a variance of 4.Find P(X > 7) .