A bag contains 63 marbles, some red and some green. The ratio of red marbles to green ones is 2:5. How many green marbles are there?

Create a data set with 8 points in it that has a mean of approximately 10 and a standard deviation of approximately 1.

Sylvia rented a boat for $16.50 per hour. her total rental fee was $49.50. for how many hours did sylvia rent the boat

Sound travels about 750 miles per hour. a) suppose it takes about 1.5 seconds to hear the echo. how far away is the canyon wall, in feet? for this i got 825 ft b) suppose you stand 1,925 feet from the canyon wall and sound the horn. how long will it take to hear the echo? (i'm stuck on this)