SOLUTION: David competes in a triathlon and has set a new goal of finishing in 17 hours and 15 minutes. The race consists of a 3.8km swin, a 180km bike ride, and a 42.2km run. David rides a

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: David competes in a triathlon and has set a new goal of finishing in 17 hours and 15 minutes. The race consists of a 3.8km swin, a 180km bike ride, and a 42.2km run. David rides a       Log On

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Question 584260: David competes in a triathlon and has set a new goal of finishing in 17 hours and 15 minutes. The race consists of a 3.8km swin, a 180km bike ride, and a 42.2km run. David rides a bike 4.5 times as fast as he swims and runs 1.6 times as fast as he bikes. If David keeps a steady pace in each event, how fast does he have to swim to reach his goal?
I have this set up as:
3.8km/x+180km/4.5x+42.2km/4.5x(1.6)=17hours 15 min.
I do not know where to go from here????

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = his speed swimming
+3.8%2Fx+%2B+180%2F%28+1.6x%29+%2B+42.2%2F%28+1.6%2A4.5%2Ax%29+=+17.25+
Multiply both sides by +1.6%2A4.5%2Ax+
+3.8%2A1.6+%2A4.5+%2B+180%2A4.5+%2B+42.2+=+17.25%2A1.6%2A4.5x+
+27.36+%2B+810+%2B+42.2++=+124.2x+
+124.2x+=+879.56+
+x+=+7.082+
He has to swim 7.082 km/hr
Check my math, but I think this method is good