Which number is not in scientific notation? (5 points) A. 9 ⋅ 1019
B. 7.8 ⋅ 106
C. 1.45 ⋅ 10−7
D. 0.33 ⋅ 10−15

10 ! in a race, nick is 50 feet in front of jay after ten seconds. how fast can nick run, if jay can run 20 feet per second?

You are designing a rectangular pet pen for your new baby puppy. you have 30 feet of fencing you would like the fencing to be 6 1/3 feet longer than the width

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.