Question

QUESTION 3 An instructor of an extremely large class (1000 students) starts grading an exam. After grading 100 of the assignments he calculates the sample average as 80 with a standard deviation of 10, He then correctly determines that he can 95% confident that the average student score is between 78.04 and 81.96. He continues grading, and after grading a total of 400 exams the sample average is 80 with a sample deviation of 20. How confident is he that the average student score is still between 78.04 and 81.96? A. Less than 95% confident 0% confident 95% confident (the confidence level does not change) More than 95% confident QUESTION 4 Using top secret University records, Dr. Rasmussen determines that 68.2% of MEEN students have IQs between 120 and 150, with an average of 135. Dr. Rasmussen also tests 4 randomly selected MEEN 260 students and finds the average IQ is 140 with a sample deviation of 20. we are 90% certain that a particular MEEN student has an IQ greater than A 135 (z0.45)(20) (zo.475)(15) O C. 140 (to.o5, 3010) 140 (to.05, 3)(15) O E. 135 (zo.45) (10) O F. 135 (z0.475)(10) O G 135 (zo.45)(15) (D H. 140 . (t0.10, 3)(10) O. 135(z0.45)(15) O B. 135

Answer 1

3) Since margin of error =

to.025,n-1 Vn

So, margin of error is inversely proportional to sample size, so as sample size increases, margin of error decreases.

In this case,

As sample size increases from 100 to 400, margin of error will decrease that will imply level of confidence will be more than 95%

ans-> D. More than 95% confident

4) We are 90% certain that a particular MEEN student has an IQ greater than

ans-> H)