Question 1

In a standard normal distribution, the range of values of z is from

Accepted Answer

A)  minus infinity to infinity 
B)  -1 to 1 
C)  0 to 1 
D)  -3.09 to 3.09 
A)  minus infinity to infinity 
B)  -1 to 1 
C)  0 to 1 
D)  -3.09 to 3.09

Question 2

The average life expectancy of computers produced by Ahmadi, Inc. is 6 years with a standard deviation of 10 months. Assume that the lives of computers are normally distributed. Suggestion: For this problem, convert ALL of the units to months.
a. What is the probability that a randomly selected computer will have a life expectancy of at least 7 years?
b. Computers that fail in less than 5 1/2 years will be replaced free of charge. What percentage
of computers are expected to be replaced free of charge?
c. What are the minimum and the maximum life expectancy of the middle 95% of the computers'
lives? Give your answers in months and do not round your answers.
d. The company is expecting that only 104 of this year's production will fail in less than 3 years and 8 months. How many computers were produced this year?

Accepted Answer

a. 0.1151
b. 27.5
c.

Question 3

Z is a standard normal random variable. What is the value of Z if the area to the right of Z is 0.9803?

Accepted Answer

A)  -2.06 
B)  0.4803 
C)  0.0997 
D)  3.06 
A)  -2.06 
B)  0.4803 
C)  0.0997 
D)  3.06

Question 4

For a standard normal distribution, determine the probabilities of obtaining the following z values. It is helpful to draw a normal distribution for each case and show the corresponding area.
a. Greater than zero
b. Between -2.4 and -2.0
c. Less than 1.6
d. Between -1.9 to 1.7
e. Between 1.5 and 1.75

Accepted Answer

a. 0.5
b.

Question 5

Exhibit 6-7
The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces.
-Refer to Exhibit 6-7. What is the probability that a randomly selected item will weigh more than 10 ounces?

Accepted Answer

A)  0.3413 
B)  0.8413 
C)  0.1587 
D)  0.5000 
A)  0.3413 
B)  0.8413 
C)  0.1587 
D)  0.5000

Question 6

Exhibit 6-4
fx) =1/10) e-x/10 x ≥ 0
-Refer to Exhibit 6-4. The mean of x is

Accepted Answer

A)  0.10 
B)  10 
C)  100 
D)  1,000 
A)  0.10 
B)  10 
C)  100 
D)  1,000

Question 7

The life expectancy of computer terminals is normally distributed with a mean of 4 years and a standard deviation of 10 months.
a. What is the probability that a randomly selected terminal will last more than 5 years?
b. What percentage of terminals will last between 5 and 6 years?
c. What percentage of terminals will last less than 4 years?
d. What percentage of terminals will last between 2.5 and 4.5 years?
e. If the manufacturer guarantees the terminals for 3 years and will replace them if they malfunction), what percentage of terminals will be replaced?

Accepted Answer

a. 0.1151

Question 8

The average starting salary of this year's MBA students is $35,000 with a standard deviation of $5,000. Furthermore, it is known that the starting salaries are normally distributed. What are the minimum and the maximum starting salaries of the middle 95% of MBA graduates?

Accepted Answer

Min. = 25,

Question 9

Given that Z is a standard normal random variable, what is the probability that -2.08 ≤ Z ≤ 1.46?

Accepted Answer

A)  0.9091 
B)  0.4812 
C)  0.4279 
D)  0.0533 
A)  0.9091 
B)  0.4812 
C)  0.4279 
D)  0.0533

Question 10

Exhibit 6-8
The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles.
-Refer to Exhibit 6-8. What is the probability that a randomly selected tire will have a life of at least 47,500 miles?

Accepted Answer

A)  0.4332 
B)  0.9332 
C)  0.0668 
D)  0.4993 
A)  0.4332 
B)  0.9332 
C)  0.0668 
D)  0.4993

Question 11

The function that defines the probability distribution of a continuous random variable is a

Accepted Answer

A)  normal function 
B)  uniform function 
C)  either normal of uniform depending on the situation 
D)  probability density function 
A)  normal function 
B)  uniform function 
C)  either normal of uniform depending on the situation 
D)  probability density function

Question 12

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?

Accepted Answer

A)  0.0000 
B)  1.0000 
C)  0.1915 
D)  0.3413 
A)  0.0000 
B)  1.0000 
C)  0.1915 
D)  0.3413

Question 13

Exhibit 6-10
A professor at a local university noted that the grades of her students were normally distributed with a mean of 73 and a standard deviation of 11.
-Refer to Exhibit 6-10. The professor has informed us that 7.93 percent of her students received grades of A. What is the minimum score needed to receive a grade of A?

Accepted Answer

A)  90.51 
B)  93.2 
C)  88.51 
D)  100.00 
A)  90.51 
B)  93.2 
C)  88.51 
D)  100.00

Question 14

Exhibit 6-1
The assembly time for a product is uniformly distributed between 6 to 10 minutes.
-Refer to Exhibit 6-1. The probability of assembling the product in 7 minutes or more is

Accepted Answer

A)  0.25 
B)  0.75 
C)  zero 
D)  1 
A)  0.25 
B)  0.75 
C)  zero 
D)  1

Question 15

A manufacturing process produces items whose weights are normally distributed. It is known that 22.57% of all the items produced weigh between 100 grams up to the mean and 49.18% weigh from the mean up to 190 grams. Determine the mean and the standard deviation.

Accepted Answer

standard d

Question 16

The z score for the standard normal distribution

Accepted Answer

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)  is always equal to zero 
B)  can never be negative 
C)  can be either negative or positive 
D)  is always equal to the mean

Question 17

Approximate the following binomial probabilities by the use of normal approximation. Twenty percent of students who finish high school do not go to college. What is the probability that in a sample of 80 high school students
a. exactly 10 will not go to college?
b. 70 or more will go to college?
c. fourteen or fewer will not go to college?

Accepted Answer

a. 0.0274

Question 18

The monthly earnings of computer programmers are normally distributed with a mean of $4,000. If only 1.7 percent of programmers have monthly incomes of less than $2,834, what is the value of the standard deviation of the monthly earnings of the computer programmers?

Accepted Answer

The answer of The monthly earnings of computer programmers are...

Question 19

A random variable X is uniformly distributed between 45 and 150.
a. Determine the probability of X = 48.
b. What is the probability of X ≤ 60?
c. What is the probability of X ≥ 50?
d. Determine the expected vale of X and its standard deviation.

Accepted Answer

a. 0.000
b

Question 20

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?

Accepted Answer

A)  1.96 
B)  -1.96 
C)  0.4505 
D)  ±1.65 
A)  1.96 
B)  -1.96 
C)  0.4505 
D)  ±1.65

In a standard normal distribution, the range of values of z is from

Z is a standard normal random variable. What is the value of Z if the area to the right of Z is 0.9803?

Exhibit 6-7 The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces. -Refer to Exhibit 6-7. What is the probability that a randomly selected item will weigh more than 10 ounces?

Exhibit 6-4 fx) =1/10) e-x/10 x ≥ 0 -Refer to Exhibit 6-4. The mean of x is

The average starting salary of this year's MBA students is $35,000 with a standard deviation of $5,000. Furthermore, it is known that the starting salaries are normally distributed. What are the minimum and the maximum starting salaries of the middle 95% of MBA graduates?

Given that Z is a standard normal random variable, what is the probability that -2.08 ≤ Z ≤ 1.46?

Exhibit 6-8 The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. -Refer to Exhibit 6-8. What is the probability that a randomly selected tire will have a life of at least 47,500 miles?

The function that defines the probability distribution of a continuous random variable is a

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?

Exhibit 6-1 The assembly time for a product is uniformly distributed between 6 to 10 minutes. -Refer to Exhibit 6-1. The probability of assembling the product in 7 minutes or more is

A manufacturing process produces items whose weights are normally distributed. It is known that 22.57% of all the items produced weigh between 100 grams up to the mean and 49.18% weigh from the mean up to 190 grams. Determine the mean and the standard deviation.

The z score for the standard normal distribution

The monthly earnings of computer programmers are normally distributed with a mean of $4,000. If only 1.7 percent of programmers have monthly incomes of less than $2,834, what is the value of the standard deviation of the monthly earnings of the computer programmers?

A random variable X is uniformly distributed between 45 and 150. a. Determine the probability of X = 48. b. What is the probability of X ≤ 60? c. What is the probability of X ≥ 50? d. Determine the expected vale of X and its standard deviation.

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?

Data and Statistics

Descriptive Statistics: Tabular and Graphical Displays

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Sampling and Sampling Distributions

Interval Estimation

Hypothesis Tests

Comparisons Involving Means, Experimental Design, and Analysis of Variance

Comparisons Involving Proportions and a Test of Independence

Simple Linear Regression

Multiple Regression

Filters

Exam 6: Continuous Probability Distributions

In a standard normal distribution, the range of values of z is from

Z is a standard normal random variable. What is the value of Z if the area to the right of Z is 0.9803?

Exhibit 6-7 The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces. -Refer to Exhibit 6-7. What is the probability that a randomly selected item will weigh more than 10 ounces?

Exhibit 6-4 fx) =1/10) e-x/10 x ≥ 0 -Refer to Exhibit 6-4. The mean of x is

The average starting salary of this year's MBA students is $35,000 with a standard deviation of $5,000. Furthermore, it is known that the starting salaries are normally distributed. What are the minimum and the maximum starting salaries of the middle 95% of MBA graduates?

Given that Z is a standard normal random variable, what is the probability that -2.08 ≤ Z ≤ 1.46?

Exhibit 6-8 The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. -Refer to Exhibit 6-8. What is the probability that a randomly selected tire will have a life of at least 47,500 miles?

The function that defines the probability distribution of a continuous random variable is a

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?

Exhibit 6-1 The assembly time for a product is uniformly distributed between 6 to 10 minutes. -Refer to Exhibit 6-1. The probability of assembling the product in 7 minutes or more is

A manufacturing process produces items whose weights are normally distributed. It is known that 22.57% of all the items produced weigh between 100 grams up to the mean and 49.18% weigh from the mean up to 190 grams. Determine the mean and the standard deviation.

The z score for the standard normal distribution

The monthly earnings of computer programmers are normally distributed with a mean of $4,000. If only 1.7 percent of programmers have monthly incomes of less than $2,834, what is the value of the standard deviation of the monthly earnings of the computer programmers?

A random variable X is uniformly distributed between 45 and 150. a. Determine the probability of X = 48. b. What is the probability of X ≤ 60? c. What is the probability of X ≥ 50? d. Determine the expected vale of X and its standard deviation.

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?

Data and Statistics

Descriptive Statistics: Tabular and Graphical Displays

Descriptive Statistics: Numerical Measures

Introduction to Probability

Discrete Probability Distributions

Sampling and Sampling Distributions

Interval Estimation

Hypothesis Tests

Comparisons Involving Means, Experimental Design, and Analysis of Variance

Comparisons Involving Proportions and a Test of Independence

Simple Linear Regression

Multiple Regression

Filters