SOLUTION: Help please, The speed of the current in a river is 2mph. Jay travels 20 miles upstream and then 20 miles downstream in a total time of hours. Find the speed of the boat. Le

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Question 169828: Help please,
The speed of the current in a river is 2mph. Jay travels 20 miles upstream and then 20 miles downstream in a total time of hours. Find the speed of the boat.
Let s be the speed of the boat.
Thanks
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
BELIEVE YOU LEFT OUT THE HOUR FIGURE????
The speed of the current in a river is 2mph. Jay travels 20 miles upstream and then 20 miles downstream in a total time of 5 1/3 hours. Find the speed of the boat. Let s be the speed of the boat.
D=ST
T=D/S
5.33=20/(S-2)+20/(S+2)
5.33=(20[S+2]+20[S-2])/(S+2)(S-2)
5.33=(20S+40+20S-40)/(S^2-4)
5.33=40S/(S^2-4)
5.33S^2-21.333=40S
5.33S^2-40S-21.333=0
uSING THE QUADRATIC EQUATIONS=%28-b%2B-sqrt%28b%5E2-4%2Aa%2Ac%29%29%2F%282%2Aa%29WE GET:
S=(40+-SQRT[-40^2-4*5.33*-21.333])/2*5.333
S=(40+-SQRT[1,600+455])/10.6667
S=(40+-SQRT2,055)/10.6667
S=(40+-SQRT45.333)/10.667
S=(40+45.333)/10.667
S=85.333/10.667
S=8 MPH. ANS FOR THE SPEED OF THE BOAT IN CALM WATERS.