There are 2,100 bacteria in a circular petri dish. the dish has a radius of 40 millimeters. what is the approximate population density? (use 3.14 for π)

area of a circle = πr2
0.02 bacteria per square millimeter
0.42 bacteria per square millimeter
2.39 bacteria per square millimeter
52.5 bacteria per square millimeter

Isuck at math ; ^; m a student solved this problem and said the answer is 3 feet. chase had a roll of ribbon that contained 7 7/8  feet of ribbon. he cut off one piece that was 3 5/8  feet long and another piece that was 1 1/4  feet from the roll. how much ribbon was left on the roll? is the student's answer reasonable? yes, the answer is reasonable. no, the answer is not reasonable. it should be about 2 feet. no, the answer is not reasonable. it should be about 13 feet. no, the answer is not reasonable. it should be about 4 feet.

Which of the following transformations will always produce a congruent figure?

In which direction does the left side of the graph of this function point? a(x) = 3x - x2 + 4x - 2