A striped marlin can swim at a rate of 70 miles per hour. Is this a faster or slower rate than a sailfish, which takes 30 minutes to swim 40 miles? Show your work.

Let's do the work shall we ...

this is going to be a ratio problem.

Striped Marlin:

70 miles / One hour (Or 60 minutes)

Sailfish:

40 miles / 30 minutes.

Since 30 minutes is only one half of 60 minutes, all we have to do is multiply the sailfish ratio by 2 in order to receive the correct mph.

(40miles/30 minutes) x2 = (80 miles/60 minutes (or one hour)).

Therefore, the sailfish is faster! 80 miles per hour is faster than the 70 mph marlin.