## Question

Find the confidence interval for the given values of o, n, x, and confidence level.

o = 13, n = 47, x = 37, confidence = 0.87

Round final answers to 2 decimal places.

Question 2

Find the confidence interval for the given values of o, n, x, and confidence level.

0 = 1.9, n = 24, x = 5.9, confidence = 0.98

Round final answers to 2 decimal places.

Question 3

Find the confidence interval for the given values of S, n, x, and confidence level, using the it distribution.

S = 39.6, n = 24, x = 90, confidence = 0.8

Round final answers to 2 decimal places.

Question 4

Professor Smith has to grade assignments each week for her math class. From previous experience, she knows the average amount of time it takes each week per student is normally distributed with a standard deviation of 1.4 minutes per student. Last week, she had to grade assignments for 23 students, and her sample mean for that week was 4.85 minutes per student.

Round all your answers to 2 decimal places.

a. Find the critical z-score for a 99% confidence interval for the average amount of time it takes per student to grade assignments.

b. Find the margin of error for a 99% confidence interval for the average amount of time it takes per student to grade assignments.

C. State the 99% confidence interval by filling in the blanks

d. Interpret your results. The blanks represent your answers in part c.

Select your answer from one the following options.

a. 99% of assignments will take between and minutes to grade.

b. Every individual student's assignment will take between -- and -- minutes to grade.

c. For 99% of samples of 23 students, the sample mean will be between and minutes.

d. The true average amount of time (calculated over many weeks) spent grading an individual student's assignment is between and minutes.

Question 5

Mike is investigating possible careers. He has decided he will only consider careers with an average salary higher than $46000. He collects a sample of 10 job postings for computer programmers, and finds a sample mean salary of $43420, and a sample standard deviation of $4800. Mike is trying to decide whether he should continue to consider computer programming, or remove it from his list of possible careers.

a. Find the critical t-score for a 95% confidence interval for the average salary of a computer programmer. Round your answer to 2 decimal places.

b. Find the margin of error for a 95% confidence interval for the average salary of a computer programmer. Round your answer to the nearest whole number.

c. State the 95% confidence interval for the average salary by filling in the blanks. Round your answers to the nearest whole numbers.

d. Interpret your results. Is Mike's hope for an average salary of 46000 feasible?

Select your answer from one the following options.

(a) No, with 95% certainty the average salary is less than (46000).

(b) Yes, Mike should collect more data because (46000) is within the confidence interval, and therefore feasible.

Question 6

Yoonie is a personnel manager in a large corporation. Each month she must review 20 of the employees.From past experience,she knows the amount of time it will take is normally distributed with a standard devation of 1.3 hours. This month, when she completed the 20 reviews, her sample mean was 4.44 hours.

a. Find the critical z-score for a 91% confidence interval for the average amount of time it takes to complete 20 reviews. Round your answer to 2 decimal places.

b. Find the margin of error for a 91% confidence interval for the amount of time it will take to complete the 20 reviews. Round your answer to 2 decimal places.

c. State the 91% confidence interval by filling in the blanks. Round your answers to 2 decimal places.

d. Interpret your results. The blanks represent your answers in part C.

Select your answer from one the following options.

a. 91% of reviews will take between___ and ____hours to complete.

b. Every employee review will take between ___ and ____ hours.

c. For 91% of samples of 20 employees, the sample mean time for reviews will be between _____ and ____ hours.

d. The true average amount of time (calculated over many months) spent reviewing employees is between ___ and ____ hours.

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