ZuoTi.Pro
Question

A professor found that historically, the scores on the final exam tend to follow a normal...

A professor found that historically, the scores on the final exam tend to follow a normal distribution.  A random sample of nine test scores from the current class had a mean score of 187.9 points and a sample standard deviation of 32.4 points. Find the 90% confidence interval for the population mean score of the current class.

  • A.

    [167.81, 207.99]

  • B.

    [ 170.13 , 205.67]

  • C.

    [ 166.73, 209.07]

  • D.

    None of these answers are correct.

business   economics   
0 0
Add a comment Improve this question Transcribed image text
Next > < Previous
Sort answers by oldest

Homework Answers

Answer #1
For a normal distribution, 90% of the values fall within 1.65 standard
deviations from the mean.
Mean 187.9
Standard deviation 32.4
(187.9 + (1.65*32.4)< 90% of values < (187.9+(1.65*32.4)
The 90% confidence interval lies between
[134.44 , 241.36]
D) None of these answers are correct.
0 0
Add a comment
Know the answer?
Add Answer to:
A professor found that historically, the scores on the final exam tend to follow a normal...
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Log In

Sign Up

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions

  • Consider the following point estimators, W, X, Y, and Z of μ: W = (x1 +...

    Consider the following point estimators, W, X, Y, and Z of μ: W = (x1 + x2)/2; X = (2x1 + x2)/3; Y = (x1 + 3x2)/4; and Z = (2x1 + 3x2)/5. Assuming that x1 and x2 have both been drawn independently from a population with mean μ and variance σ2 then which of the following is true...Which of the following point estimators is the most efficient? A. Z B. W C. X D. Y An estimator is unbiased...

  • 7) A retired statistics professor has recorded final exam results for decades. The mean final exam...

    7) A retired statistics professor has recorded final exam results for decades. The mean final exam score for the population of her students is 82.4 with a standard deviation of 6.5 . In the last year, her standard deviation seems to have changed. She bases this on a random sample of 25 students whose final exam scores had a mean of 80 with a standard deviation of 4.2 . Test the professor's claim that the current standard deviation is different...

  • A sample of 10 students record their scores on the final exam for their statistics class....

    A sample of 10 students record their scores on the final exam for their statistics class. The mean of the sample is 81 with sample standard deviation 7 points. Analysis of the 10 sample values indicated that the population is approximately normal. We wish to find the 95% confidence interval for the population mean test scores. What is the confidence level, c? Which of the following is correct? To find the confidence interval, a z-critical value should be used because...

  • Assume that scores on the verbal portion of the GRE (Graduate Record Exam) follow the normal...

    Assume that scores on the verbal portion of the GRE (Graduate Record Exam) follow the normal distribution with mean score 151 and standard deviation 7 points, while the quantitative portion of the exam has scores following the normal distribution with mean 153 and standard deviation 7.67. Use this information to answer the following: (Please round to two decimal places) a) Find the score of a student who scored in the 80th percentile on the Quantitative Reasoning section of the exam....

  • From a random sample of 66 students in an introductory finance class that uses​ group-learning techniques, the mean exam...

    From a random sample of 66 students in an introductory finance class that uses​ group-learning techniques, the mean examination score was found to be 79.79 and the sample standard deviation was 2.7. For an independent random sample of 99 students in another introductory finance class that does not use​ group-learning techniques, the sample mean and standard deviation of exam scores were 72.14 and 8.8 respectively. Estimate with 90​% confidence the difference between the two population mean​ scores; do not assume...

  • Example 3 The scores on a midterm exam follow a normal distribution with an average of...

    Example 3 The scores on a midterm exam follow a normal distribution with an average of 80.4% and a standard deviation of 10.9%. Let X represent the score of a given student on this midterm exam. 1. What is the probability that a randomly selected student scores above a 90%? 2. What is the probability that a randomly selected student scores between 80% and 90%? 3. What is the 60th percentile score for this midterm exam?

  • In a large economics class, the professor announced that the scores of a recent exam were...

    In a large economics class, the professor announced that the scores of a recent exam were normally distributed in a domain from 51 to 87. Using the Empirical Rule on µ ± 3σ to estimate σ (that is, σ=[upper limit-lower limit]/6), how many students would you need to sample in order to construct a 90 percent confidence interval of the population mean score with an allowable error of ± 2? (Hint: use the critical value Z0.05=1.645 for a 90 percent...

  • The professor of a introductory calculus class has stated that, historically, the distribution of final exam...

    The professor of a introductory calculus class has stated that, historically, the distribution of final exam grades in the course resemble a Normal distribution with a mean final exam mark of μ=63μ=63% and a standard deviation of σ=9σ=9%. If using/finding zz-values, use three decimals. (a) What is the probability that a random chosen final exam mark in this course will be at least 73%? Answer to four decimals. (b) In order to pass this course, a student must have a...

  • Suppose we are interested to construct a 95% confidence interval of the mean exam score. A...

    Suppose we are interested to construct a 95% confidence interval of the mean exam score. A random sample of 36 scores is taken and gives a sample mean (sample mean score) of 68. EBM will be the largest O a when the population standard deviation is 12 points, when the population standard deviation is 18 points. OC when the population standard deviation is 15 points when the population standard deviation is 20 points Od b. Suppose we are interested to...

  • Scores on an exam follow an approximately Normal distribution with a mean of 76.4 and a...

    Scores on an exam follow an approximately Normal distribution with a mean of 76.4 and a standard deviation of 6.1 points. What percent of students scored below 70 points?

ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT