Question 1

The life of a light bulb is exponentially distributed with a mean of 1,000 hours.What is the probability that the bulb will last more than 1,200 hours?

Accepted Answer

A) .3012 
B) .3679 
C) .4345 
D) .6988 
A) .3012 
B) .3679 
C) .4345 
D) .6988

Question 2

What is the probability that a standard normal random variable will be between 0.3 and 3.2?

Accepted Answer

A) .6179 
B) .3814 
C) .3808 
D) .9993 
A) .6179 
B) .3814 
C) .3808 
D) .9993

Question 3

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 from the population is between 29.75 and 30.5 inches long?

Accepted Answer

A) .4332 
B) .4878 
C) .0546 
D) .9210 
A) .4332 
B) .4878 
C) .0546 
D) .9210

Question 4

The exponential probability distribution is based on a continuous random variable.

Accepted Answer

A) True 
 B)False

Question 5

A manufacturer of personal computers tests competing brands and finds that the amount of energy they require is normally distributed with a mean of 285 kwh and a standard deviation of 9.1 kwh.If the lowest 25 percent and the highest 30 percent are not included in a second round of tests,what are the upper and lower limits for the energy amounts of the remaining computers?

Accepted Answer

A)  $\left[ \begin{array} { l l } 
269.76 & 300.24
\end{array} \right]$ 
B)  $\left[ \begin{array} { l l } 
269.76 & 289.78
\end{array} \right]$ 
C)  $[ 280.22$ $ \quad$$ \quad$$289.78 ]$ 
D)  $\left[ \begin{array} { l l } 
280.22 & 300.24
\end{array} \right]$ 
A)  $\left[ \begin{array} { l l } 
269.76 & 300.24
\end{array} \right]$ 
B)  $\left[ \begin{array} { l l } 
269.76 & 289.78
\end{array} \right]$ 
C)  $[ 280.22$ $ \quad$$ \quad$$289.78 ]$ 
D)  $\left[ \begin{array} { l l } 
280.22 & 300.24
\end{array} \right]$

Question 6

The average time a subscriber spends reading the local newspaper is 49 minutes.Assume the standard deviation is 16 minutes and that the times are normally distributed.What is the probability a subscriber will spend at least 1 hour reading the paper?

Accepted Answer

A) .9987 
B) .7549 
C) .2451 
D) .0013 
A) .9987 
B) .7549 
C) .2451 
D) .0013

Question 7

Find z when the area between z and -z is .9030.

Accepted Answer

A) 1.50 
B) 1.30 
C) 0.12 
D) 1.66 
A) 1.50 
B) 1.30 
C) 0.12 
D) 1.66

Question 8

The normal approximation of the binomial distribution is appropriate when:

Accepted Answer

A) np ≥ 5 
B) n(1 - p)≥ 5 
C) np ≤ 5 
D) n(1 - p)≤ 5 and np ≤ 5 
E) np ≥ 5 and n(1 - p)≥ 5 
A) np ≥ 5 
B) n(1 - p)≥ 5 
C) np ≤ 5 
D) n(1 - p)≤ 5 and np ≤ 5 
E) np ≥ 5 and n(1 - p)≥ 5

Question 9

The number of defective pencils in a lot of 1000 is an example of a continuous random variable.

Accepted Answer

A) True 
 B)False

Question 10

All continuous random variables are normally distributed.

Accepted Answer

A) True 
 B)False

Question 11

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 probability that a randomly selected depth is less than 3.60 m?

Accepted Answer

A) .72 
B) .80 
C) .46 
D) .32 
A) .72 
B) .80 
C) .46 
D) .32

Question 12

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 will take at least 50 minutes?

Accepted Answer

A) .77 
B) .40 
C) .60 
D) .23 
A) .77 
B) .40 
C) .60 
D) .23

Question 13

The area under the curve of a valid continuous probability distribution must ____________.

Accepted Answer

A) Equal 1 
B) Be between 0 and 1 
C) Be infinite 
D) Be less than 1 
A) Equal 1 
B) Be between 0 and 1 
C) Be infinite 
D) Be less than 1

Question 14

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 31 inches long?

Accepted Answer

A) 0.00 
B) 1.00 
C) .8289 
D) .5987 
A) 0.00 
B) 1.00 
C) .8289 
D) .5987

Question 15

During the past six months,73.2 percent of US households purchased sugar.Assume that these expenditures are approximately normally distributed with a mean of $8.22 and a standard deviation of $1.10.Find the probability that a household spent less than $5.00 on sugar.

Accepted Answer

A) .9983 
B) 0.000 
C) 1.00 
D) 0.0017 
A) .9983 
B) 0.000 
C) 1.00 
D) 0.0017

Question 16

Which of the following statements is not a property of the normal probability distribution?

Accepted Answer

A) The normal distribution is symmetric. 
B) 95.44 percent of all possible observed values of the random variable x are within plus or minus three standard deviations of the population mean. 
C) The mean,median,and mode are equal. 
D) The area under the normal curve to the right of the mean is equal to the area under the normal curve to the left of the mean. 
E) All of these answers are properties of the normal distribution. 
A) The normal distribution is symmetric. 
B) 95.44 percent of all possible observed values of the random variable x are within plus or minus three standard deviations of the population mean. 
C) The mean,median,and mode are equal. 
D) The area under the normal curve to the right of the mean is equal to the area under the normal curve to the left of the mean. 
E) All of these answers are properties of the normal distribution.

Question 17

A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.What percentage of the time will the number of boxes received weekly be between 180 and 210?

Accepted Answer

A) 69.15% 
B) 19.15% 
C) 53.28% 
D) 15.87% 
A) 69.15% 
B) 19.15% 
C) 53.28% 
D) 15.87%

Question 18

A continuous random variable may assume only integer values in a given interval.

Accepted Answer

A) True 
 B)False

Question 19

A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.What percentage of the time will the number of boxes received weekly be greater than 210 or less than 180?

Accepted Answer

A) 69.15% 
B) 46.72% 
C) 19.15% 
D) 15.87% 
A) 69.15% 
B) 46.72% 
C) 19.15% 
D) 15.87%

Question 20

The z value tells us the number of standard deviations that a value x is from the mean.

Accepted Answer

A) True 
 B)False

The life of a light bulb is exponentially distributed with a mean of 1,000 hours.What is the probability that the bulb will last more than 1,200 hours?

What is the probability that a standard normal random variable will be between 0.3 and 3.2?

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 from the population is between 29.75 and 30.5 inches long?

The exponential probability distribution is based on a continuous random variable.

The average time a subscriber spends reading the local newspaper is 49 minutes.Assume the standard deviation is 16 minutes and that the times are normally distributed.What is the probability a subscriber will spend at least 1 hour reading the paper?

Find z when the area between z and -z is .9030.

The normal approximation of the binomial distribution is appropriate when:

The number of defective pencils in a lot of 1000 is an example of a continuous random variable.

All continuous random variables are normally distributed.

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 probability that a randomly selected depth is less than 3.60 m?

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 will take at least 50 minutes?

The area under the curve of a valid continuous probability distribution must ____________.

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 31 inches long?

During the past six months,73.2 percent of US households purchased sugar.Assume that these expenditures are approximately normally distributed with a mean of $8.22 and a standard deviation of $1.10.Find the probability that a household spent less than $5.00 on sugar.

Which of the following statements is not a property of the normal probability distribution?

A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.What percentage of the time will the number of boxes received weekly be between 180 and 210?

A continuous random variable may assume only integer values in a given interval.

A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.What percentage of the time will the number of boxes received weekly be greater than 210 or less than 180?

The z value tells us the number of standard deviations that a value x is from the mean.

An Introduction to Business Statistics

Descriptive Statistics: Tabular and Graphical Methods

Descriptive Statistics: Numerical Methods

Probability

Discrete Random Variables

Sampling and Sampling Distributions

Confidence Intervals

Hypothesis Testing

Comparing Two Means and Two Proportions

Filters

Exam 6: Continuous Random Variables

The life of a light bulb is exponentially distributed with a mean of 1,000 hours.What is the probability that the bulb will last more than 1,200 hours?

What is the probability that a standard normal random variable will be between 0.3 and 3.2?

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 from the population is between 29.75 and 30.5 inches long?

The exponential probability distribution is based on a continuous random variable.

The average time a subscriber spends reading the local newspaper is 49 minutes.Assume the standard deviation is 16 minutes and that the times are normally distributed.What is the probability a subscriber will spend at least 1 hour reading the paper?

Find z when the area between z and -z is .9030.

The normal approximation of the binomial distribution is appropriate when:

The number of defective pencils in a lot of 1000 is an example of a continuous random variable.

All continuous random variables are normally distributed.

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 probability that a randomly selected depth is less than 3.60 m?

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 will take at least 50 minutes?

The area under the curve of a valid continuous probability distribution must ____________.

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 31 inches long?

During the past six months,73.2 percent of US households purchased sugar.Assume that these expenditures are approximately normally distributed with a mean of $8.22 and a standard deviation of $1.10.Find the probability that a household spent less than $5.00 on sugar.

Which of the following statements is not a property of the normal probability distribution?

A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.What percentage of the time will the number of boxes received weekly be between 180 and 210?

A continuous random variable may assume only integer values in a given interval.

A plant manager knows that the number of boxes of supplies received weekly is normally distributed with a mean of 200 and a standard deviation of 20.What percentage of the time will the number of boxes received weekly be greater than 210 or less than 180?

The z value tells us the number of standard deviations that a value x is from the mean.

An Introduction to Business Statistics

Descriptive Statistics: Tabular and Graphical Methods

Descriptive Statistics: Numerical Methods

Probability

Discrete Random Variables

Sampling and Sampling Distributions

Confidence Intervals

Hypothesis Testing

Comparing Two Means and Two Proportions

Filters