The difference between an observational study and an experiment is that

in an observational study, only one group is studied, and in an experiment, two groups are studied.

in an observational study, the researchers do not control treatment, and in an experiment, they do.

in an experiment, cause-and-effect is analyzed, and in an observational study, it is not.

in an experiment, one group is studied over a short period of time, and in an observational study, the group is studied over a longer period of time.

Option b is true.

Step-by-step explanation:

Given that the difference between an observational study and an experiment is one out of the 4 options given.

Option I is wrong because in observation, also sometimes two groups are studied.

Option II is right, because observation is as it is observing what is happening but in an experiment they change certain things as required and study

Option III is wrong because in both cases, cause and effect is analyzed.

Option IV is wrong because both groups are normally studied for an equal necessary amount of time period.

we know that

applying the law of sines

°

so

∠j=18°

∠k=29°

∠l=180-(18+29)=133°

the answer part a) is

the measure of angle k is  ≈29°

part b)  the measure of angle k could also be

(180-29)=151°

so

∠j=18°

∠k=151°

∠l=180-(18+151)=11°

the answer part b) is

the measure of angle k could also be 151°

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d

gimmee one of those gold crowns!

~coco