An instructor in a college class recently gave an exam that

An instructor in a college class recently gave an exam that was worth a total of 100 points. The instructor inadvertently made the exam harder than he had intended. The scores were very symmetric, but the average score for his students was 54 and the standard deviation of the scores was 4 points. The instructor is considering 2 different strategies for rescaling the exam results:

Method 1:Add 20 points to everyone\'s score.

Method 2:Multiply everyone\'s score by 1.5.

Which of the following are true?

Select all that apply.

Select one or more:

A) Method 1 will increase the standard deviation of the students\' scores

B) Method 2 will increase the standard deviation of the students\' scores.

C) Method 1 will decrease the standard deviation of the students\' scores.

D) Method 2 will decrease the standard deviation of the students\' scores.

Solution

An instructor in a college class recently gave an exam that was worth a total of 100 points. The instructor inadvertently made the exam harder than he had intended. The scores were very symmetric, but the average score for his students was 54 and the standard deviation of the scores was 4 points. The instructor is considering 2 different strategies for rescaling the exam results:

Method 1:Add 20 points to everyone\'s score.

Method 2:Multiply everyone\'s score by 1.5.

Which of the following are true?

Select all that apply.

Select one or more:

A) Method 1 will increase the standard deviation of the students\' scores

B) Method 2 will increase the standard deviation of the students\' scores.

C) Method 1 will decrease the standard deviation of the students\' scores.

D) Method 2 will decrease the standard deviation of the students\' scores.

Both will not decrease the SD

Method 1 will not change the SD

Method 2 will increase the SD by 1.5 times( new SD=4*1.5=6)