Question 1

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of 1. The probability that Z values are larger than ________ is 0.6985.

Accepted Answer

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

Question 2

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 3

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 4

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. What proportion of customers having to hold more than 4.5 minutes will hang up before placing an order?

Accepted Answer

A)  0.22313 
B)  0.48658 
C)  0.51342 
D)  0.77687

Question 5

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of 1. The probability that Z is less than -2.20 is ________.

Accepted Answer

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

Question 6

Let X represent the amount of time it takes a student to park in the library parking lot at the university. If we know that the distribution of parking times can be modeled using an exponential distribution with a mean of 4 minutes, find the probability that it will take a randomly selected student more than 10 minutes to park in the library lot.

Accepted Answer

A)  0.917915 
B)  0.670320 
C)  0.329680 
D)  0.082085

Question 7

Times spent watching TV every week by first graders follow an exponential distribution with mean 10 hours. The probability that a given first grader spends less than 20 hours watching TV is ________.

Accepted Answer

The answer of Times spent watching TV every week by...

Question 8

TABLE 6-3
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 6-3, what is the probability that the time interval between two consecutive defective light bulbs will be between 10 and 20 minutes?

Accepted Answer

The answer of TABLE 6-3
Suppose the time interval between two...

Question 9

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, 15% of the products require more than ________ minutes for assembly.

Accepted Answer

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

Question 10

TABLE 6-2
John has two jobs. For daytime work at a jewelry store he is paid $15,000 per month, plus a commission. His monthly commission is normally distributed with mean $10,000 and standard deviation $2,000. At night he works as a waiter, for which his monthly income is normally distributed with mean $1,000 and standard deviation $300. John's income levels from these two sources are independent of each other.
-Referring to Table 6-2, John's commission from the jewelry store will be between what two values symmetrically distributed around the population mean 90% of the time?

Accepted Answer

The answer of TABLE 6-2
John has two jobs. For daytime...

Question 11

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 10 and 12 minutes.

Accepted Answer

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

Question 12

Times spent watching TV every week by first graders follow an exponential distribution with mean 10 hours. The probability that a given first grader spends between 10 and 15 hours watching TV is ________.

Accepted Answer

The answer of Times spent watching TV every week by...

Question 13

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 14

Patients arriving at an outpatient clinic follow an exponential distribution at a rate of 15 patients per hour. What is the probability that a randomly chosen arrival to be more than 5 minutes?

Accepted Answer

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

Question 15

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%. What is the probability that the time lapsed between two consecutive trades will be between 13 and 14 seconds?

Accepted Answer

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

Question 16

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%. The middle 86.64% of the students will score between which two scores?

Accepted Answer

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

Question 17

The amount of tea leaves in a can from a particular production line is normally distributed withμ = 110 grams and σ = 25 grams. What is the probability that a randomly selected can will contain between 100 and 120 grams of tea leaves?

Accepted Answer

The answer of The amount of tea leaves in a...

Question 18

Patients arriving at an outpatient clinic follow an exponential distribution with mean 15 minutes. What is the probability that a randomly chosen arrival to be less than 15 minutes?

Accepted Answer

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

Question 19

TABLE 6-4
The interval between consecutive hits at a web site is assumed to follow an exponential distribution with an average of 40 hits per minute.
-Referring to Table 6-4, what is the average time between consecutive hits?

Accepted Answer

The answer of TABLE 6-4
The interval between consecutive hits at...

Question 20

TABLE 6-2
John has two jobs. For daytime work at a jewelry store he is paid $15,000 per month, plus a commission. His monthly commission is normally distributed with mean $10,000 and standard deviation $2,000. At night he works as a waiter, for which his monthly income is normally distributed with mean $1,000 and standard deviation $300. John's income levels from these two sources are independent of each other.
-Referring to Table 6-2, the probability is 0.10 that John's commission from the jewelry store is more than how much in a given month?

Accepted Answer

The answer of TABLE 6-2
John has two jobs. For daytime...

Exam 6: The Normal Distribution and Other Continuous Distributions

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of 1. The probability that Z values are larger than ________ is 0.6985.

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?

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.

Suppose Z has a standard normal distribution with a mean of 0 and standard deviation of 1. The probability that Z is less than -2.20 is ________.

Times spent watching TV every week by first graders follow an exponential distribution with mean 10 hours. The probability that a given first grader spends less than 20 hours watching TV 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. So, 15% of the products require more than ________ minutes for assembly.

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 10 and 12 minutes.

Times spent watching TV every week by first graders follow an exponential distribution with mean 10 hours. The probability that a given first grader spends between 10 and 15 hours watching TV is ________.

Patients arriving at an outpatient clinic follow an exponential distribution at a rate of 15 patients per hour. What is the probability that a randomly chosen arrival to be more than 5 minutes?

The amount of tea leaves in a can from a particular production line is normally distributed with μ = 110 grams and σ = 25 grams. What is the probability that a randomly selected can will contain between 100 and 120 grams of tea leaves?

Patients arriving at an outpatient clinic follow an exponential distribution with mean 15 minutes. What is the probability that a randomly chosen arrival to be less than 15 minutes?

TABLE 6-4 The interval between consecutive hits at a web site is assumed to follow an exponential distribution with an average of 40 hits per minute. -Referring to Table 6-4, what is the average time between consecutive hits?

The amount of tea leaves in a can from a particular production line is normally distributed withμ = 110 grams and σ = 25 grams. What is the probability that a randomly selected can will contain between 100 and 120 grams of tea leaves?