Question

In a class of 100 students, the average score in the final exam was 72 out...

In a class of 100 students, the average score in the final exam was 72 out of 100 with a standard deviation of 5. A statistician computes the following approximate 95% confidence interval 72 ± 1.96 · 5/ √ 100 = 72 ± 0.98. Is he correct or not? Explain.

Math   Statistics-And-Probability   
0 0
Add a commentTranscribed image text
Next >

Homework Answers

Answer #1

Solution:

Given that,

The equation is not correct.

When standard deviation is unknown , then we use t - distribution.

From the given problem , there is a z - distribution, then the given equation is not correct.

The correct equation is,

At 95% confidence level the t is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

t /2,df = t0.025,99 = 1.984

72 ± 1.984 · 5/ √ 100 = 72 ± 0.992.

0 0
Know the answer?
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
Similar Questions
In your psychology class, the mean exam score is 72 and the standard deviation is 12....
In your psychology class, the mean exam score is 72 and the standard deviation is 12. You scored 78. In your biology class, the mean exam score is 56 and the standard deviation is 5. You scored 66. If your professors grade "on a curve" (i.e., according to the distribution of scores), for which exam would you expect to get a better grade? (Hint: Convert your exam scores to z-scores). A) Biology B) Psychology
An instructor of a biology class believes the average final exam score for his biology class...
An instructor of a biology class believes the average final exam score for his biology class was more than 75. Suppose a sample of 25 was taken and the sample mean he observed was 78.48 and a standard deviation of 5 points. What is the value of the test statistic? Report your answer to 2 decimal places. (hint: to determine which test statistic to calculate, you must think about what methods should be used. Either one-sample t-methods, one-sample z-methods or...
Grading on the Curve: A final exam for a large class of students is constructed so...
Grading on the Curve: A final exam for a large class of students is constructed so that final exam grades follow a normal distribution with mean µ and standard deviation σ. The class is graded on the curve, which means that a final exam score of x translates into a final exam letter grade according to the following table: Grade Range A µ + σ < x B µ < x < µ + σ C µ − σ <...
1. Suppose that the average grades of an introduction to marketing course final is 70 with...
1. Suppose that the average grades of an introduction to marketing course final is 70 with a standard deviation of 5. Chris got 60 in this exam, please calculate Chris’ z-score. How do we interpret that number? 2. Cassie got 85 in this exam, please calculate Cassie’s z-score. How do we interpret that number? Now calculate what percentile Cassie’s score lies. 3. Find the interval of scores within which 95% of the students fall (z-score = ±1.96) in this exam.
A large statistics class consists of 250 students. On the final exam, the professor worries that...
A large statistics class consists of 250 students. On the final exam, the professor worries that question 13 might be unfair. He resolves to drop question 13 if less than 40% of the class correctly answers the question. After grading 125 randomly selected final exams (out of 250 taken), a student calls the professor and asks if question 13 will be dropped. The professor looks at the graded exams and notes that 46 of the 125 graded exams got question...
A professor knows that her statistics students' final exam scores have a mean of 78 and...
A professor knows that her statistics students' final exam scores have a mean of 78 and a standard deviation of 9.3. In his class, an "A" is any exam score of 90 or higher. This quarter she has 25 students in her class. What is the probability that 4 students or more will score an "A" on the final exam?
The average score of the students in one calculus class is 75, with a standard deviation...
The average score of the students in one calculus class is 75, with a standard deviation of 5. The average score of the students in statistics class is 85 with a standard deviation of 5. Which class is more variable in terms of scores?
2.27 Make-up exam: In a class of 27 students, 26 of them took an exam in...
2.27 Make-up exam: In a class of 27 students, 26 of them took an exam in class and 1 student took a make-up exam the following day. The professor graded the first batch of 26 exams and found an average score of 84 points with a standard deviation of 7 points. The student who took the make-up the following day scored 64 points on the exam. a) Does the new student's score increase or decrease the average? Increases Decreases b)...
The average score of 100 students taking a statistics test final with 70 with a standard...
The average score of 100 students taking a statistics test final with 70 with a standard deviation of seven. Assuming a normal distribution, approximately how many scored less than 60
A class of two hundred students took a calculus final. If the sample mean for thirty...
A class of two hundred students took a calculus final. If the sample mean for thirty randomly selected students was 95 percent with a (sample) standard deviation of 6.6 percent, construct a 99% confidence interval for the mean score of all students. Show all work, including the formula you are using.
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT