Algebra
posted by Jon .
The five fastest roller coasters in the world Fujiyama(Japan), Goliath(CA), Millenium Force(OH), Steel Dragon 2000(Japan), and Superman the Escape(CA). The speeds, in mph, of the first four coasters are 83,85,92,and 95, respectively. How fast can Superman the Escape travel if the average speed of all five coasters is no more than 91 mph?
A)no more than 100 mph
C)at least 100 mph
I think it's A b/c 83+85+92+95+100/5 = 91 mph. it cant be C b/c it says "at least" 100 which means it can go faster than 100 so the answer is A.

5*91>(84+85+92+95+S)
455>356+S
99>S
So the answer is in the above: Superman cannot be going 99 or faster.
check my thinking. 
if the average speed of ALL 5 coasters is no more than 91 mph then that last coaster has to be 100 mph to reach a speed of 91 on average. if superman goes at 99 then the average would be only 90.8

if it's at 100, the average would be 91 exactly