[(15 x 3) + 3] = (12-6) = N

45+3 = 6=N

48_6= N

42= N

:. N= 42

Step-by-step explanation:

:. N= 42

A.twenty names from each grade pulled blindly from a container filled with the names of the entire student body written on slips of paper

Step-by-step explanation:

Choosing from the names of the entire student body gives us a representative sample.  Choosing them blindly from a container gives us a random sample.

Choosing people walking down Main Street does not guarantee we will get students at the school.

Choosing all of the students who write in to the paper would only give us people that are interested.

Choosing students that are in Miranda's classes only represents her grade level, not the entire school.