If the volume for 3-d pyramid a is 200 cm3 and the volume for 3-d pyramid b is 800 cm3, how many times bigger is the volume of pyramid b than pyramid a?

Asurvey of 2,000 doctors showed that an average of 3 out of 5 doctors use brand x aspirin. how many doctors use brand x aspirin

Which graph has a rate of change of zero

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.