Question 1

You were told that the mean score on a statistics exam is 75 with the scores normally distributed. In addition, you know the probability of a score between 55 and 60 is 4.41% and that the probability of a score greater than 90 is 6.68%. What is the probability of a score between 55 and 95?

Accepted Answer

The answer of You were told that the mean score...

Question 2

TABLE 6-1
The manager of a surveying company believes that the average number of phone surveys completed per hour by her employees has a normal distribution. She takes a sample of 15 days output from her employees and determines the average number of surveys per hour on these days. The ordered array for this data is: 10.0, 10.1, 10.3, 10.5, 10.7, 11.2, 11.4, 11.5, 11.7,
11.8, 11.8, 12.0, 12.2, 12.2, 12.5.
-Referring to Table 6-1, construct a normal probability plot for the data.

Accepted Answer

The answer of TABLE 6-1
The manager of a surveying company...

Question 3

A food processor packages orange juice in small jars. The weights of the filled jars are approximately normally distributed with a mean of 10.5 ounces and a standard deviation of 0.3 ounce. Find the proportion of all jars packaged by this process that have weights that fall below 10.875 ounces.

Accepted Answer

The answer of A food processor packages orange juice in...

Question 4

The amount of pyridoxine (in grams) in a multiple vitamin is normally distributed with µ = 110 grams and a = 25 grams. Approximately 83% of the vitamins will have at least how many grams of pyridoxine?

Accepted Answer

The answer of The amount of pyridoxine (in grams) in...

Question 5

The amount of time necessary for assembly line workers to complete a product is a normal random variable with a mean of 15 minutes and a standard deviation of 2 minutes. So, 90% of the products require more than _____minutes for assembly.

Accepted Answer

The answer of The amount of time necessary for assembly...

Question 6

A catalog company that receives the majority of its orders by telephone conducted a study to determine how long customers were willing to wait on hold before ordering a product. The length of time was found to be a random variable best approximated by an exponential distribution with a mean equal to 3 minutes. Find the waiting time at which only 10% of the customers will continue to hold.

Accepted Answer

A)  2.3 minutes 
B)  6.9 minutes 
C)  3.3 minutes 
D)  13.8 minutes

Question 7

TABLE 6-7
A company has 125 personal computers. The probability that any one of them will require repair on a given day is 0.15.
-Referring to Table 6-7, which of the following is one of the properties required so that the binomial distribution can be used to compute the probability that no more than 2 computers will require repair on a given day?

Accepted Answer

A)  A randomly selected computer on a given day will either require a repair or will not. 
B)  The probability that two or more computers that will require repair in a given day approaches zero. 
C)  The probability that a computer that will require repair in the morning is the same as that in the afternoon. 
D)  The number of computers that will require repair in the morning is independent of the number of computers that will require repair in the afternoon.

Question 8

One of the reasons that a correction for continuity adjustment is needed when approximating the binomial distribution with a normal distribution is because the probability of getting a specific value of a random variable is zero with the normal distribution.

Accepted Answer

A) True 
 B)False

Question 9

TABLE 6-5
Suppose the time interval between two consecutive defective light bulbs from a production line has a uniform distribution over an interval from 0 to 90 minutes.
-Referring to Table 6-5, the probability is 75% that the time interval between two consecutive defective light bulbs will fall between which two values that are the same distance from the mean?

Accepted Answer

The answer of TABLE 6-5
Suppose the time interval between two...

Question 10

TABLE 6-2
The city manager of a large city believes that the number of reported accidents on any weekend has a normal distribution. She takes a sample of nine weekends and determines the number of reported accidents during each. The ordered array for this data is: 15, 46, 53, 54, 55, 76, 82, 256, 407.
-Referring to Table 6-2, the seventh standard normal quantile is _____ .

Accepted Answer

The answer of TABLE 6-2
The city manager of a large...

Question 11

As a general rule, one can use the normal distribution to approximate a binomial distribution whenever n(u - 1) is at least 5.

Accepted Answer

A) True 
 B)False

Question 12

Patients arriving at an outpatient clinic follow an exponential distribution with mean 15 minutes. What is the average number of arrivals per minute?

Accepted Answer

The answer of Patients arriving at an outpatient clinic follow...

Question 13

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of
 So 50% of the possible Z values are between ______ and ______ (symmetrically distributed about the mean).

Accepted Answer

The answer of Suppose Z has a standard normal distribution...

Question 14

You were told that the amount of time lapsed between consecutive trades on the New York Stock Exchange followed a normal distribution with a mean of 15 seconds. You were also told that the probability that the time lapsed between two consecutive trades to fall between 16 to 17 seconds was 13%. The probability that the time lapsed between two consecutive trades would fall below 13 seconds was 7%. The middle 60% of the time lapsed will fall between which two numbers?

Accepted Answer

The answer of You were told that the amount of...

Question 15

TABLE 6-3
The number of column inches of classified advertisements appearing on Mondays in a certain daily newspaper is normally distributed with population mean 320 and population standard deviation 20 inches.
-Referring to Table 6-3, a single Monday is chosen at random. State in which of the following ranges the number of column inches of classified advertisement is most likely to be:

Accepted Answer

A)  300- 320 
B)  320- 340 
C)  310- 330 
D)  330- 350

Question 16

The probability that a standard normal random variable, Z, is below 1.96 is 0.4750.

Accepted Answer

A) True 
 B)False

Question 17

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of
The probability that Z is more than 0.77 is _____ .

Accepted Answer

The answer of Suppose Z has a standard normal distribution...

Question 18

The amount of time necessary for assembly line workers to complete a product is a normal random variable with a mean of 15 minutes and a standard deviation of 2 minutes. The probability is_____ that a product is assembled in between 15 and 21 minutes.

Accepted Answer

The answer of The amount of time necessary for assembly...

Question 19

Which of the following about the normal distribution is not true?

Accepted Answer

A)  About 2/3 of the observations fall within ±1 standard deviation from the mean. 
B)  It is a discrete probability distribution. 
C)  Its parameters are the mean, µ, and standard deviation, a. 
D)  Theoretically, the mean, median, and mode are the same.

Question 20

To determine the probability of getting fewer than 3 events of interest in a binomial distribution, you will find the area under the normal curve for X = 3.5 and below.

Accepted Answer

A) True 
 B)False

Exam 6: The Normal Distribution and Other Continuous Distributions

You were told that the mean score on a statistics exam is 75 with the scores normally distributed. In addition, you know the probability of a score between 55 and 60 is 4.41% and that the probability of a score greater than 90 is 6.68%. What is the probability of a score between 55 and 95?

A food processor packages orange juice in small jars. The weights of the filled jars are approximately normally distributed with a mean of 10.5 ounces and a standard deviation of 0.3 ounce. Find the proportion of all jars packaged by this process that have weights that fall below 10.875 ounces.

The amount of pyridoxine (in grams) in a multiple vitamin is normally distributed with µ = 110 grams and a = 25 grams. Approximately 83% of the vitamins will have at least how many grams of pyridoxine?

The amount of time necessary for assembly line workers to complete a product is a normal random variable with a mean of 15 minutes and a standard deviation of 2 minutes. So, 90% of the products require more than _____minutes for assembly.

One of the reasons that a correction for continuity adjustment is needed when approximating the binomial distribution with a normal distribution is because the probability of getting a specific value of a random variable is zero with the normal distribution.

As a general rule, one can use the normal distribution to approximate a binomial distribution whenever n(u - 1) is at least 5.

Patients arriving at an outpatient clinic follow an exponential distribution with mean 15 minutes. What is the average number of arrivals per minute?

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of So 50% of the possible Z values are between and (symmetrically distributed about the mean).

The probability that a standard normal random variable, Z, is below 1.96 is 0.4750.

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of The probability that Z is more than 0.77 is _____ .

The amount of time necessary for assembly line workers to complete a product is a normal random variable with a mean of 15 minutes and a standard deviation of 2 minutes. The probability is_____ that a product is assembled in between 15 and 21 minutes.

Which of the following about the normal distribution is not true?

To determine the probability of getting fewer than 3 events of interest in a binomial distribution, you will find the area under the normal curve for X = 3.5 and below.

Exam 6: The Normal Distribution and Other Continuous Distributions

You were told that the mean score on a statistics exam is 75 with the scores normally distributed. In addition, you know the probability of a score between 55 and 60 is 4.41% and that the probability of a score greater than 90 is 6.68%. What is the probability of a score between 55 and 95?

A food processor packages orange juice in small jars. The weights of the filled jars are approximately normally distributed with a mean of 10.5 ounces and a standard deviation of 0.3 ounce. Find the proportion of all jars packaged by this process that have weights that fall below 10.875 ounces.

The amount of pyridoxine (in grams) in a multiple vitamin is normally distributed with µ = 110 grams and a = 25 grams. Approximately 83% of the vitamins will have at least how many grams of pyridoxine?

The amount of time necessary for assembly line workers to complete a product is a normal random variable with a mean of 15 minutes and a standard deviation of 2 minutes. So, 90% of the products require more than _____minutes for assembly.

One of the reasons that a correction for continuity adjustment is needed when approximating the binomial distribution with a normal distribution is because the probability of getting a specific value of a random variable is zero with the normal distribution.

As a general rule, one can use the normal distribution to approximate a binomial distribution whenever n(u - 1) is at least 5.

Patients arriving at an outpatient clinic follow an exponential distribution with mean 15 minutes. What is the average number of arrivals per minute?

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of So 50% of the possible Z values are between ______ and ______ (symmetrically distributed about the mean).

The probability that a standard normal random variable, Z, is below 1.96 is 0.4750.

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of The probability that Z is more than 0.77 is _____ .

The amount of time necessary for assembly line workers to complete a product is a normal random variable with a mean of 15 minutes and a standard deviation of 2 minutes. The probability is_____ that a product is assembled in between 15 and 21 minutes.

Which of the following about the normal distribution is not true?

To determine the probability of getting fewer than 3 events of interest in a binomial distribution, you will find the area under the normal curve for X = 3.5 and below.

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of So 50% of the possible Z values are between and (symmetrically distributed about the mean).