A submarine left Pearl Harbor and traveled east. An aircraft carrier left four hours later traveling 30 mph in an effort to catch up to the submarine. After traveling 8 hours, the aircraft carrier finally caught up to the submarine. What was the submarine’s average speed?

Question

A submarine left Pearl Harbor and traveled east. An aircraft carrier left four hours later traveling 30 mph in an effort to catch up to the submarine.  After traveling 8 hours, the aircraft carrier finally caught up to the submarine.  What was the submarine’s average speed?

mathhelper · Accepted Answer

Speed of sub ---- x mph After 8 hours, at x mph, the sub went 8x miles after 4 hours, at 30 mph, the carrier went 120 miles 8x = 120 x = .....

somia · Answer

i got this thanks distance of submarine = distance of aircraft S.t = S.t S(8+4) = 30.8 12S =240 S=2 mph

mathhelper · Answer

I actually messed up my times, should have been:

Speed of sub ---- x mph

time of travel of the sub is 12 hours
time of travel of the carrier is 8 hrs

After 12 hours, at x mph, the sub went 12x miles
after 8 hours, at 30 mph, the carrier went 240 miles

12x = 240
x = 20 mph

You clearly meant to say S = 20 , not S = 2
You also obviously caught my error.