Question 1

The mean of any normal distribution is always zero.

Accepted Answer

A) True 
 B)False

Question 2

A continuous probability distribution represents a random variable having an infinite number of outcomes that may assume any number of values within an interval.

Accepted Answer

A) True 
 B)False

Question 3

If Z is a standard normal random variable, the area between z = 0.0 and z =1.30 is 0.4032, while the area between z = 0.0 and z = 1.50 is 0.4332. What is the area between z = -1.30 and z = 1.50?

Accepted Answer

A) 0.0300. 
B) 0.0668. 
C) 0.0968. 
D) 0.8364. 
A) 0.0300. 
B) 0.0668. 
C) 0.0968. 
D) 0.8364.

Question 4

If the random variable X is exponentially distributed with parameter $\lambda$ = 3, then P(X $\geq$ 2), up to 4 decimal places, is:

Accepted Answer

A) 0.3333. 
B) 0.5000. 
C) 0.6667. 
D) 0.0025. 
A) 0.3333. 
B) 0.5000. 
C) 0.6667. 
D) 0.0025.

Question 5

If the random variable X is exponentially distributed with parameter F1F1F1S1F1F1F10 = 1.75, then P(1.5 F1F1F1S1F1F1F10 X F1F1F1S1F1F1F10 3.8), up to 4 decimal places, is:

Accepted Answer

A) 0.0711. 
B) 0.0473. 
C) 0.1184. 
D) 0.4739. 
A) 0.0711. 
B) 0.0473. 
C) 0.1184. 
D) 0.4739.

Question 6

A supermarket receives a delivery each morning at a time that varies uniformly between 5:00 and 7:00am.
a. Find the probability that the delivery on a given morning will occur between 5:30 and 5:45am.
b. What is the expected time of delivery?
c. Determine the standard deviation of the delivery time.
d. Find the probability that the time of delivery will be within half a standard deviation of the expected time.

Accepted Answer

a. 0.125.
b. F1F1F1S

Question 7

Which of the following is true for a normal distribution?

Accepted Answer

A) It is unimodal. 
B) It is symmetrical. 
C) It has a bell shape. 
D) All of these choices are correct. 
A) It is unimodal. 
B) It is symmetrical. 
C) It has a bell shape. 
D) All of these choices are correct.

Question 8

If Z is a standard normal random variable, find the value z for which: 
a. $P ( 0 \leq Z \leq z ) = 0.35$
b. $P ( - z \leq Z \leq z ) = 0.142$
c. $P ( - z \leq Z \leq 0 ) = 0.441$

Accepted Answer

a. 1.04.
b

Question 9

The length of time patients must wait to see a doctor at an emergency room in a large hospital is uniformly distributed between 40 minutes and 3 hours.
a. What is the probability that a patient would have to wait between 50 minutes and 2 hours?
b. What is the probability that a patient would have to wait exactly 1 hour?
c. Find the expected waiting time.
d. Find the standard deviation of the waiting time.

Accepted Answer

a. 0.50.
b. 0.0.
c.

Question 10

Using the standard normal curve, the area between z = 0 and z = 3.50 is about 0.50.

Accepted Answer

A) True 
 B)False

Question 11

Using the standard normal curve, the z-score representing the 10th percentile is 1.28.

Accepted Answer

A) True 
 B)False

Question 12

A bank has determined that the monthly balances of the saving accounts of its customers are normally distributed, with an average balance of $1200 and a standard deviation of $250. What proportions of the customers have monthly balances:
a. less than $1000?
b. more than $1125?
c. between $950 and $1075?

Accepted Answer

a. 0.2119.

Question 13

In the normal distribution, the curve is skewed.

Accepted Answer

A) True 
 B)False

The mean of any normal distribution is always zero.

A continuous probability distribution represents a random variable having an infinite number of outcomes that may assume any number of values within an interval.

If Z is a standard normal random variable, the area between z = 0.0 and z =1.30 is 0.4032, while the area between z = 0.0 and z = 1.50 is 0.4332. What is the area between z = -1.30 and z = 1.50?

If the random variable X is exponentially distributed with parameter $\lambda$ = 3, then P(X $\geq$ 2), up to 4 decimal places, is:

If the random variable X is exponentially distributed with parameter  = 1.75, then P(1.5  X  3.8), up to 4 decimal places, is:

Which of the following is true for a normal distribution?

If Z is a standard normal random variable, find the value z for which: a. $P ( 0 \leq Z \leq z ) = 0.35$ b. $P ( - z \leq Z \leq z ) = 0.142$ c. $P ( - z \leq Z \leq 0 ) = 0.441$

Using the standard normal curve, the area between z = 0 and z = 3.50 is about 0.50.

Using the standard normal curve, the z-score representing the 10th percentile is 1.28.

In the normal distribution, the curve is skewed.

What Is Statistics

Types of Data, Data Collection and Sampling

Graphical Descriptive Techniques Nominal Data

Graphical Descriptive Techniques Numerical Data

Numerical Descriptive Measures

Probability

Random Variables and Discrete Probability Distributions

Statistical Inference and Sampling Distributions

Estimation: Describing a Single Population

Estimation: Comparing Two Populations

Hypothesis Testing: Describing a Single Population

Hypothesis Testing: Comparing Two Populations

Additional Tests for Nominal Data: Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Time-Series Analysis and Forecasting

Index Numbers

Filters

Exam 8: Continuous Probability Distributions

The mean of any normal distribution is always zero.

A continuous probability distribution represents a random variable having an infinite number of outcomes that may assume any number of values within an interval.

If Z is a standard normal random variable, the area between z = 0.0 and z =1.30 is 0.4032, while the area between z = 0.0 and z = 1.50 is 0.4332. What is the area between z = -1.30 and z = 1.50?

If the random variable X is exponentially distributed with parameter λ\lambdaλ = 3, then P(X ≥\geq≥ 2), up to 4 decimal places, is:

If the random variable X is exponentially distributed with parameter  = 1.75, then P(1.5  X  3.8), up to 4 decimal places, is:

Which of the following is true for a normal distribution?

If Z is a standard normal random variable, find the value z for which: a. P(0≤Z≤z)=0.35P ( 0 \leq Z \leq z ) = 0.35P(0≤Z≤z)=0.35 b. P(−z≤Z≤z)=0.142P ( - z \leq Z \leq z ) = 0.142P(−z≤Z≤z)=0.142 c. P(−z≤Z≤0)=0.441P ( - z \leq Z \leq 0 ) = 0.441P(−z≤Z≤0)=0.441

Using the standard normal curve, the area between z = 0 and z = 3.50 is about 0.50.

Using the standard normal curve, the z-score representing the 10th percentile is 1.28.

In the normal distribution, the curve is skewed.

What Is Statistics

Types of Data, Data Collection and Sampling

Graphical Descriptive Techniques Nominal Data

Graphical Descriptive Techniques Numerical Data

Numerical Descriptive Measures

Probability

Random Variables and Discrete Probability Distributions

Statistical Inference and Sampling Distributions

Estimation: Describing a Single Population

Estimation: Comparing Two Populations

Hypothesis Testing: Describing a Single Population

Hypothesis Testing: Comparing Two Populations

Additional Tests for Nominal Data: Chi-Squared Tests

Simple Linear Regression and Correlation

Multiple Regression

Time-Series Analysis and Forecasting

Index Numbers

Filters

If the random variable X is exponentially distributed with parameter $\lambda$ = 3, then P(X $\geq$ 2), up to 4 decimal places, is:

If Z is a standard normal random variable, find the value z for which: a. $P ( 0 \leq Z \leq z ) = 0.35$ b. $P ( - z \leq Z \leq z ) = 0.142$ c. $P ( - z \leq Z \leq 0 ) = 0.441$