SOLUTION: You are to travel from point A to point B and return. On the trip from A to B, you travel at thirty miles per hour. How fast would you have to travel from B to A in order to averag

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: You are to travel from point A to point B and return. On the trip from A to B, you travel at thirty miles per hour. How fast would you have to travel from B to A in order to averag      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 293799: You are to travel from point A to point B and return. On the trip from A to B, you travel at thirty miles per hour. How fast would you have to travel from B to A in order to average sixty miles per hour for the round trip?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
You are to travel from point A to point B and return. On the trip from A to B, you travel at thirty miles per hour. How fast would you have to travel from B to A in order to average sixty miles per hour for the round trip?
:
Think about this, assume it's 30 mi one way:
To average 60 mph, you have cover 60 mi in 1 hr which is the round trip distance
You have used up 1 hr just to cover 30 mi, therefore it is impossible
:
Look what happens when you solve this in the conventional way
Let s = speed required to accomplish this
write a time equation
d%2F30 + d%2Fs = %282d%29%2F60
every term has d, divide thru by d and you have
1%2F30 + 1%2Fs = 2%2F60
Multiply by 60 s to get rid of the denominators
:
2s + 60 = 2s; obviously, this is not possible