# The lifetimes of light bulbs of a particular type are normally

Question 1 of 20 5.0 Points

The lifetimes of light bulbs of a particular type are normally distributed with a mean of 270 hours and a standard deviation of 11 hours. What percentage of the bulbs has lifetimes that lie within 2 standard deviations of the mean on either side?

Apply the 68-95-99.7 rule to this questions.

A. 68%

B. 1005

C. 99.7%

D. 95%

Question 2 of 20 5.0 Points

A study of the amount of time it takes a mechanic to rebuild the transmission for a 1992 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.77 hours. Assume that a random sample of 40 mechanics is selected and the mean rebuild time of the sample is computed. Assuming the mean times are normally distributed, what percentage of sample means are greater than 7.7 hours?

A. 0.62%

B. 34.46%

C. 65.54%

D. 99.38%

Question 3 of 20 5.0 Points

The area under the standard normal curve between 1 and 2 is equal to 0.1359. Scores on a particular aptitude test are normally distributed with a mean of 100 and a standard deviation of 10. Which of the following are equal to 13.59%?

a) The percentage of scores between 120 and 130

b) The percentage of scores between 110 and 120

c) The percentage of scores between 80 and 90

d) The percentage of scores between 90 and 120

A. b

B. b, c

C. d

D. a, b

Question 4 of 20 5.0 Points

The scores on a certain test are normally distributed with a mean score of 58 and a standard deviation of 4. What is the likelihood that a sample of 90 students will have a mean score of at least 58.4216?

A. 0.8413

B. 0.3413

C. 0.3174

D. 0.1587

Question 5 of 20 5.0 Points

If light bulbs have lives that are normally distributed with a mean of

2500 hours and a standard deviation of 500 hours, what percentage of

light bulbs have a life less than 2500 hours?

A. About 25%

B. About 50%

C. About 75%

D. About 68%

Question 6 of 20 5.0 Points

The volumes of soda in quart soda bottles are normally distributed with a mean of 32.3 oz and a standard deviation of 1.2 oz. What is the probability that the volume of soda in a randomly selected bottle will be less than 32 oz?

A. 0.5012

B. 0.5010

C. 0.4015

D. 0.4013

Question 7 of 20 5.0 Points

A math teacher gives two different tests to measure students’ aptitude for math. Scores on the first test are normally distributed with a mean of 24 and a standard deviation of 4.5. Scores on the second test are normally distributed with a mean of 70 and a standard deviation of 11.3. Assume that the two tests use different scales to measure the same aptitude. If a student scores 29 on the first test, what would be his equivalent score on the second test? (That is, find the score that would put him in the same percentile.)

A. 87

B. 85

C. 86

D. 83

Question 8 of 20 5.0 Points

The lifetimes of projector bulbs of a particular type are normally distributed with a mean of 470 hours and a standard deviation of 15 hours. What percentage of the bulbs has lifetimes that lie within 2 standard deviations of the mean on either side?

Apply the 68-95-99.7 rule to this question.

A. 68%

B. 99.7%

C. 95%

D. 100%

Question 9 of 20 5.0 Points

Which of the following statements concerning the standard normal curve is/are true (if any)?

a) The area under the standard normal curve to the left of -3 is zero.

b) The area under the standard normal curve between any two z-scores is greater than zero.

c) The area under the standard normal curve between two z-scores will be negative if both z-scores are negative.

d) The area under the standard normal curve to the left of any z-score is less than 1.

A. a, b

B. b, d

C. a, c

D. a

Question 10 of 20 5.0 Points

A bank’s loan officer rates applicants for credit. The ratings are normally distributed with a mean of 200 and a standard deviation of 50. If an applicant is randomly selected, find the probability of a rating that is between 225 and 275.

A. 0.2416

B. 0.2418

C. 0.2417

D. 0.2420

Question 11 of 20 5.0 Points

A final exam in Math 160 has a mean of 73 with standard deviation 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 70?

A. 19.46%

B. 12.85%

C. 2.87%

D. 13.46%

Question 12 of 20 5.0 Points

The amount of Jen’s monthly electric bill is normally distributed with a mean of \$160 and a standard deviation of \$14. Fill in the blanks.

95% of her electric bills are between __________ and __________.

Apply the 68-95-99.7 rule to this question.

A. \$140, \$190

B. \$132, \$190

C. \$140, \$188

D. \$132, \$188

Question 13 of 20  5.0 Points

Which of the following statements concerning areas under the standard normal curve is/are true?

a) If a z-score is negative, the area to its right is greater than 0.5.

b) If the area to the right of a z-score is less than 0.5, the z-score is negative.

c) If a z-score is positive, the area to its left is less than 0.5.

A. a, c

B. b, c

C. a, b

D. a

Question 14 of 20  5.0 Points

The diameters of pencils produced by a certain machine are normally distributed with a mean of 0.30 inches and a standard deviation of 0.01 inches. In a random sample of 460 pencils, approximately how many would you expect to have a diameter less than 0.293 inches?

A. 123

B. 118

C. 112

D. 111

Question 15 of 20  5.0 Points

The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 88 inches, and a standard deviation of 10 inches. What is the likelihood that the mean annual precipitation during 25 randomly picked years will be less than 90.8 inches?

A. 0.4192

B. 0.5808

C. 0.0808

D. 0.9192

Question 16 of 20  5.0 Points

The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.25 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.24 inches?

A. 79.13%

B. 82.46%

C. 84.13%

D. 84.46%

Question 17 of 20  5.0 Points

The mean score on the exit examination for an urban high school is 63 with a standard deviation of 8. What is the mean of the distribution of sample means with a sample size of 9?

A. 62

B. 63

C. 63.5

D. 64

Question 18 of 20  5.0 Points

The systolic blood pressures of the patients at a hospital are normally distributed with a mean of 136 mm Hg and a standard deviation of 12 mm Hg. Find the two blood pressures having these properties: the mean is midway between them and 76.98% of all blood pressures are between them.

A. 121.6, 152.4

B. 121.6, 150.4

C. 123.6, 150.4

D. 122.6, 148.4

Question 19 of 20  5.0 Points

The mean score on the exit examination for an urban high school is 63 with a standard deviation of 9. What is the standard deviation of the distribution of sample means with a sample size of 9?

A. 2

B. 3

C. 4

D. 4.1

Question 20 of 20  5.0 Points

At one college, GPA’s are normally distributed with a mean of 2.9 and a standard deviation of 0.6. Find the 70th percentile.

A. 3.53

B. 3.42

C. 3.23

D. 3.13 Calculate your paper price
Pages (550 words)
Approximate price: -

Why Work with Us Top Quality and Well-Researched Papers

We always make sure that writers follow all your instructions precisely. You can choose your academic level: high school, college/university or professional, and we will assign a writer who has a respective degree. Professional and Experienced Academic Writers

We have a team of professional writers with experience in academic and business writing. Many are native speakers and able to perform any task for which you need help. Free Unlimited Revisions

If you think we missed something, send your order for a free revision. You have 10 days to submit the order for review after you have received the final document. You can do this yourself after logging into your personal account or by contacting our support. Prompt Delivery and 100% Money-Back-Guarantee

All papers are always delivered on time. In case we need more time to master your paper, we may contact you regarding the deadline extension. In case you cannot provide us with more time, a 100% refund is guaranteed. Original & Confidential

We use several writing tools checks to ensure that all documents you receive are free from plagiarism. Our editors carefully review all quotations in the text. We also promise maximum confidentiality in all of our services. 24/7 Customer Support

Our support agents are available 24 hours a day 7 days a week and committed to providing you with the best customer experience. Get in touch whenever you need any assistance.

Try it now!

## Calculate the price of your order

Total price:
\$0.00

How it works?

Follow these simple steps to get your paper done Place your order

Fill in the order form and provide all details of your assignment. Proceed with the payment

Choose the payment system that suits you most. Receive the final file

Once your paper is ready, we will email it to you.

Our Services

No need to work on your paper at night. Sleep tight, we will cover your back. We offer all kinds of writing services.  ## Essay Writing Service

No matter what kind of academic paper you need and how urgent you need it, you are welcome to choose your academic level and the type of your paper at an affordable price. We take care of all your paper needs and give a 24/7 customer care support system.  Admission Essays & Business Writing Help

An admission essay is an essay or other written statement by a candidate, often a potential student enrolling in a college, university, or graduate school. You can be rest assurred that through our service we will write the best admission essay for you.  Editing Support

Our academic writers and editors make the necessary changes to your paper so that it is polished. We also format your document by correctly quoting the sources and creating reference lists in the formats APA, Harvard, MLA, Chicago / Turabian.  Revision Support

If you think your paper could be improved, you can request a review. In this case, your paper will be checked by the writer or assigned to an editor. You can use this option as many times as you see fit. This is free because we want you to be completely satisfied with the service offered.