SOLUTION: A cruise ship left the Bahamas two hours before a speedboat. The boats traveled in opposite directions. The speedboat traveled at 25 mph for two hours. After this amount of time, t

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: A cruise ship left the Bahamas two hours before a speedboat. The boats traveled in opposite directions. The speedboat traveled at 25 mph for two hours. After this amount of time, t      Log On


   

Question 888312: A cruise ship left the Bahamas two hours before a speedboat. The boats traveled in opposite directions. The speedboat traveled at 25 mph for two hours. After this amount of time, the vessels were 90 miles apart. Find the cruise ship's speed.
I need a lot of help to even understand a little
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I call this a " head start " problem. The cruise
ship has a +2+ hr head start.
Let +d%5B1%5D+ = the cruse ship's head start
in miles.
Let +s+ = the cruise ship's speed in miles / hr
(1) +d%5B1%5D+=+2s+
This is the head start
------------------
After 2 hrs, the speedboat has traveled
+d%5B2%5D+=+25%2A2+
+d%5B2%5D+=+50+ mi
------------------
The vessels are +90+ mi apart after +2+ hrs
The cruise ship has traveled +2s+ again in the +2+ hrs
since the speedboat left
-----------------------------------
+2s+%2B+2s+%2B+50+=+90+
+4s+=+90+-+50+
+4s+=+40+
+s+=+10+
The cruise ship's speed is 10 mi/hr
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This makes sense because in +4+ hrs the cruise ship
traveled +90+-+50+=+40+ mi
+40%2F4+=+10+ mi/hr
Hope this helps