A teacher wants to investigate whether listening to music while taking a math test increases scores. He instructs half of his 36 students to listen to music while taking a test and the other half to not listen to music during the test. To
determine who listens and who does not, the teacher identifies the two students who scored highest on the last test
and randomly instructs one to listen to music and one to not. The teacher does the same for the next two highest-
scoring students and continues in this manner until each student has their instructions. Which of the following best
describes this plan?
O This is a cluster sample.
O This is an observational study.
O This is a stratified random sample.
O This is an experiment with blocking.
O This is a completely randomized experiment.

For your question: "A teacher wants to investigate whether listening to music while taking a math test increases scores. He instructs half

of his 36 students to listen to music while taking a test and the other half to not listen to music during the test. To

determine who listens and who does not, the teacher identifies the two students who scored highest on the last test

and randomly instructs one to listen to music and one to not. The teacher does the same for the next two highest-

scoring students and continues in this manner until each student has their instructions. Which of the following best

describes this plan?"

The answer is D

she played for 18.75 hours.

step-by-step explanation:

if she played 2/4 of a hour on tuesday. and there is 60 minutes in an hour and 60 divided by 4 is 7.5. and she played 2/4 of an hour on thursday then again 60 divided by 4 is 7.5, you add 7.5+7.5=56.25. now you have to do 1/4 of an hour, it equals 3.75. now you have to add them all up. 3.75+7.5+7.5=18.75

i hope this and i hope you get it right. it took me a while to get this done for you. : )