is 310 ch.6

d. Poisson probability distribution

A continuous probability distribution that is useful in describing the time, or space, between occurrences of an event is a(n) a. normal probability distribution b. uniform probability distribution c. exponential probability distribution d. Poisson probability distribution

d. 1/(b - a)

A continuous random variable is uniformly distributed between a and b. The probability density function between a and b is a. zero b. (a - b) c. (b - a) d. 1/(b - a)

a. all values in an interval or collection of intervals

A continuous random variable may assume a. all values in an interval or collection of intervals b. only integer values in an interval or collection of intervals c. only fractional values in an interval or collection of intervals d. all the positive integer values in an interval

b. the number of standard deviations of an observation is to the left of the mean

A negative value of Z indicates that a. the number of standard deviations of an observation is to the right of the mean b. the number of standard deviations of an observation is to the left of the mean c. a mistake has been made in computations, since Z cannot be negative d. the data has a negative mean

c. a standard normal distribution

A normal distribution with a mean of 0 and a standard deviation of 1 is called a. a probability density function b. an ordinary normal curve c. a standard normal distribution d. none of these alternatives is correct

a. is a continuous probability distribution

A normal probability distribution a. is a continuous probability distribution b. is a discrete probability distribution c. can be either continuous or discrete d. must have a standard deviation of 1

b. with a mean of 0 and a standard deviation of 1

A standard normal distribution is a normal distribution a. with a mean of 1 and a standard deviation of 0 b. with a mean of 0 and a standard deviation of 1 c. with any mean and a standard deviation of 1 d. with any mean and any standard deviation

d. None of these alternatives is correct.

A uniform probability distribution is a continuous probability distribution where the probability that the random variable assumes a value in any interval of equal length is a. different for each interval b. the same for each interval c. at least one d. None of these alternatives is correct.

b. continuity correction factor

A value of 0.5 that is added and/or subtracted from a value of x when the continuous normal distribution is used to approximate the discrete binomial distribution is called a. 50% of the area under the normal curve b. continuity correction factor c. factor of conversion d. all of the alternatives are correct answers

a. is a continuous distribution

An exponential probability distribution a. is a continuous distribution b. is a discrete distribution c. can be either continuous or discrete d. must be normally distributed

d. 0.729

Consider a binomial probability experiment with n = 3 and p = 0.1. Then, the probability of x = 0 is a. 0.0000 b. 0.0001 c. 0.001 d. 0.729

d. the height of the function at x

For a continuous random variable x, the probability density function f(x) represents a. the probability at a given value of x b. the area under the curve at x c. the area under the curve to the right of x d. the height of the function at x

c. the z is to the left of the mean

For a normal distribution, a negative value of z indicates a. a mistake has been made in computations, because z is always positive b. the area corresponding to the z is negative c. the z is to the left of the mean d. the z is to the right of the mean

a. 0.9267

For a standard normal distribution, the probability of obtaining a z value between -1.9 to 1.7 is a. 0.9267 b. 0.4267 c. 1.4267 d. 0.5000

b. 0.0146

For a standard normal distribution, the probability of obtaining a z value between -2.4 to -2.0 is a. 0.4000 b. 0.0146 c. 0.0400 d. 0.5000

d. 0.9452

For a standard normal distribution, the probability of obtaining a z value of less than 1.6 is a. 0.1600 b. 0.0160 c. 0.0016 d. 0.9452

c. 0.5

For a standard normal distribution, the probability of z 0 is a. zero b. -0.5 c. 0.5 d. one

b. the height of the function is the same for each value of x

For a uniform probability density function, a. the height of the function cannot be larger than one b. the height of the function is the same for each value of x c. the height of the function is different for various values of x d. the height of the function decreases as x increases

d. almost zero

For any continuous random variable, the probability that the random variable takes on exactly a specific value is a. 1.00 b. 0.50 c. any value between 0 to 1 d. almost zero

b. 0.5

For the standard normal probability distribution, the area to the left of the mean is a. -0.5 b. 0.5 c. any value between 0 to 1 d. 1

a. 0.9091

Given that Z is a standard normal random variable, what is the probability that -2.08 Z 1.46? a. 0.9091 b. 0.4812 c. 0.4279 d. 0.0533

c. 0.0570

Given that Z is a standard normal random variable, what is the probability that -2.51 Z -1.53? a. 0.4950 b. 0.4370 c. 0.0570 d. 0.9310

b. 0.9830

Given that Z is a standard normal random variable, what is the probability that Z -2.12? a. 0.4830 b. 0.9830 c. 0.017 d. 0.966

b. 1.59

Given that Z is a standard normal random variable, what is the value of Z if the are to the left of Z is 0.0559? a. 0.4441 b. 1.59 c. 0.0000 d. 1.50

d. 1.65

Given that Z is a standard normal random variable, what is the value of Z if the area between -Z and Z is 0.901? a. 1.96 b. -1.96 c. 0.4505 d. 1.65

c. -1.18

Given that Z is a standard normal random variable, what is the value of Z if the area to the left of Z is 0.119? a. 0.381 b. +1.18 c. -1.18 d. 2.36

a. 0.0000

Given that Z is a standard normal random variable, what is the value of Z if the area to the right of Z is 0.5? a. 0.0000 b. 1.0000 c. 0.1915 d. 0.3413

b. -2.13

Given that Z is a standard normal random variable, what is the value of Z if the area to the right of Z is 0.9834? a. 0.4834 b. -2.13 c. +2.13 d. Zero

a. 1.16

Given that Z is a standard normal random variable. What is the value of Z if the area between -Z and Z is 0.754? a. 1.16 b. 1.96 c. 2.0 d. 11.6

b. 1.54

Given that Z is a standard normal random variable. What is the value of Z if the area to the left of Z is 0.9382? a. 1.8 b. 1.54 c. 2.1 d. 1.77

a. 1.08

Given that Z is a standard normal random variable. What is the value of Z if the area to the right of Z is 0.1401? a. 1.08 b. 0.1401 c. 2.16 d. -1.08

d. None of these alternatives is correct.

If the mean of a normal distribution is negative, a. the standard deviation must also be negative b. the variance must also be negative c. a mistake has been made in the computations, because the mean of a normal distribution cannot be negative d. None of these alternatives is correct.

a. 0.5

In a standard normal distribution, the probability that Z is greater than 0.5 is a. 0.5 b. equal to 1 c. at least 0.5 d. 1.96

a. minus infinity to infinity

In a standard normal distribution, the range of values of z is from a. minus infinity to infinity b. -1 to 1 c. 0 to 1 d. -3.09 to 3.09

b. a continuous random variable

The exponential probability distribution is used with a. a discrete random variable b. a continuous random variable c. any probability distribution with an exponential term d. an approximation of the binomial probability distribution

d. probability density function

The function that defines the probability distribution of a continuous random variable is a a. normal function b. uniform function c. either normal of uniform depending on the situation d. probability density function

d. the mean

The highest point of a normal curve occurs at a. one standard deviation to the right of the mean b. two standard deviations to the right of the mean c. approximately three standard deviations to the right of the mean d. the mean

a. is always equal to zero

The mean of a standard normal probability distribution a. is always equal to zero b. can be any value as long as it is positive c. can be any value d. is always greater than zero

d. 0.25

The probability density function for a uniform distribution ranging between 2 and 6 is a. 4 b. undefined c. any positive value d. 0.25

a. is equal to zero

The probability that a continuous random variable takes any specific value a. is equal to zero b. is at least 0.5 c. depends on the probability density function d. is very close to 1.0

b. 0.5

The random variable x is known to be uniformly distributed between 70 and 90. The probability of x having a value between 80 to 95 is a. 0.75 b. 0.5 c. 0.05 d. 1

b. is always equal to one

The standard deviation of a standard normal distribution a. is always equal to zero b. is always equal to one c. can be any positive value d. can be any value

a. a continuous random variable

The uniform probability distribution is used with a. a continuous random variable b. a discrete random variable c. a normally distributed random variable d. any random variable, as long as it is not nominal

a. all continuous probability distributions

The uniform, normal, and exponential distributions are a. all continuous probability distributions b. all discrete probability distributions c. can be either continuous or discrete, depending on the data d. all the same distributions

c. can be either negative or positive

The z score for the standard normal distribution a. is always equal to zero b. can never be negative c. can be either negative or positive d. is always equal to the mean

a. -2.06

Z is a standard normal random variable. What is the value of Z if the area to the right of Z is 0.9803? a. -2.06 b. 0.4803 c. 0.0997 d. 3.06

b. is the mean of the distribution

The center of a normal curve is a. always equal to zero b. is the mean of the distribution c. cannot be negative d. is the standard deviation

d. 1.16

Z is a standard normal random variable. What is the value of Z if the area between -Z and Z is 0.754? a. 0.377 b. 0.123 c. 2.16 d. 1.16

b. 1.22

Z is a standard normal random variable. What is the value of Z if the area to the right of Z is 0.1112? a. 0.3888 b. 1.22 c. 2.22 d. 3.22

d. wider and flatter

Larger values of the standard deviation result in a normal curve that is a. shifted to the right b. shifted to the left c. narrower and more peaked d. wider and flatter

b. 50%

The ages of students at a university are normally distributed with a mean of 21. What percentage of the student body is at least 21 years old? a. It could be any value, depending on the magnitude of the standard deviation b. 50% c. 21% d. 1.96%

a. 0.0683

Use the normal approximation to the binomial distribution to answer this question. Fifteen percent of all students at a large university are absent on Mondays. If a random sample of 12 names is called on a Monday, what is the probability that four students are absent? a. 0.0683 b. 0.0213 c. 0.0021 d. 0.1329

b. a value of 0.5 is added and/or subtracted from the value of x

When a continuous probability distribution is used to approximate a discrete probability distribution a. a value of 0.5 is added and/or subtracted from the area b. a value of 0.5 is added and/or subtracted from the value of x c. a value of 0.5 is added to the area d. a value of 0.5 is subtracted from the area

d. The standard deviation must be 1

Which of the following is not a characteristic of the normal probability distribution? a. The mean, median, and the mode are equal b. The mean of the distribution can be negative, zero, or positive c. The distribution is symmetrical d. The standard deviation must be 1

c. 99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean

Which of the following is not a characteristic of the normal probability distribution? a. symmetry b. The total area under the curve is always equal to 1. c. 99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean d. The mean is equal to the median, which is also equal to the mode.

a. 0.000

X is a normally distributed random variable with a mean of 12 and a standard deviation of 3. The probability that X equals 19.62 is a. 0.000 b. 0.0055 c. 0.4945 d. 0.9945

c. 0.0069

X is a normally distributed random variable with a mean of 22 and a standard deviation of 5. The probability that X is less than 9.7 is a. 0.000 b. 0.4931 c. 0.0069 d. 0.9931

a. 0.0029

X is a normally distributed random variable with a mean of 5 and a variance of 4. The probability that X is greater than 10.52 is a. 0.0029 b. 0.0838 c. 0.4971 d. 0.9971

d. 0.9190

X is a normally distributed random variable with a mean of 8 and a standard deviation of 4. The probability that X is between 1.48 and 15.56 is a. 0.0222 b. 0.4190 c. 0.5222 d. 0.9190

d. 0.8181

Z is a standard normal random variable. The P (-1.20 Z 1.50) equals a. 0.0483 b. 0.3849 c. 0.4332 d. 0.8181

d. 0.0829

Z is a standard normal random variable. The P (1.20 Z 1.85) equals a. 0.4678 b. 0.3849 c. 0.8527 d. 0.0829

d. 0.0771

Z is a standard normal random variable. The P (1.41 < Z < 2.85) equals a. 0.4978 b. 0.4207 c. 0.9185 d. 0.0771

c. 0.7953

Z is a standard normal random variable. The P(-1.5 < Z < 1.09) equals a. 0.4322 b. 0.3621 c. 0.7953 d. 0.0711

b. 0.0558

Z is a standard normal random variable. The P(-1.96 Z -1.4) equals a. 0.8942 b. 0.0558 c. 0.475 d. 0.4192

b. 0.1303

Z is a standard normal random variable. The P(1.05 < Z < 2.13) equals a. 0.8365 b. 0.1303 c. 0.4834 d. 0.3531

d. 0.0174

Z is a standard normal random variable. The P(Z > 2.11) equals a. 0.4821 b. 0.9821 c. 0.5 d. 0.0174