To test the effect of music on productivity, a group of assembly line workers are given portable mp3 players to play whatever music they choose while working for one month. for another month, they work without music. the order of the two treatments for each worker is determined randomly. this is
(a) an observational study.
(b) a completely randomized experiment.
(c) a block design.
(d) a matched pairs experiment.
(e) impossible to classify unless more details of the study are provided.

(d) a matched pairs experiment.

Step-by-step explanation:

The correct answer is option D that is d) a matched pairs experiment.

A matched pair experiment is special case of randomize block design. This experiment can be used when the statement has two treatment conditions and subjects are grouped into pair based on some treatment. For each pair, random treatments are assigned to the subjects. It is an improvement over complete randomized design.

This is an experiment because a treatment (the MP3 players) was assigned to different members of the sample(the assembly line workers) randomly.

x² + 3x + 7 = 0       [ax² + bx + c]

a = 1

b = 3

c = 7

quadratic formula:

    (+/- is this ±)

plug in the numbers into the variables

your answer is a

you need to give us more information since we can't answer