SOLUTION: Debbie traveled by Boat 5 miles upstream to fish. Because of the 4mph current, it took her 20 minutes longer to get there than to return. How fast will her boat go in still water
Algebra.Com
Question 222063: Debbie traveled by Boat 5 miles upstream to fish. Because of the 4mph current, it took her 20 minutes longer to get there than to return. How fast will her boat go in still water?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Debbie traveled by boat 5 miles upstream to fish.
Because of the 4 mph current, it took her 20 minutes longer to get there
than to return.
How fast will her boat go in still water?
:
Let s = boat speed in still water
then
(s-4) = speed upstream
and
(s+4) = speed down stream
:
Convert 20 min to hrs: 20/60 = hr
:
Write a time equation: time =
Upstream time = downstream time + 20 minutes (1/3 hr)
= +
:
To clear out these denominators, multiply equation by 3(s+4)(s-4)
3(s+4)(s-4)* = 3(s+4)(s-4)* + *3(s+4)(s-4)
Results in
:
15(s+4) = 15(s-4) + (s+4)(s-4)
:
15s + 60 = 15s - 60 + s^2 - 16
:
0 = 15s - 15s - 60 - 60 + s^2 - 16
:
0 = s^2 - 136
:
s^2 = 136
s =
s = 11.66 mph speed in still water
:
:
Check solution on calc: (speed up = 7.66 and speed down = 15.66)
5/7.66 - 5/15.66 = .3333 which is 1/3 of an hr
RELATED QUESTIONS
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the... (answered by ankor@dixie-net.com)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the... (answered by ankor@dixie-net.com)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 4... (answered by ankor@dixie-net.com)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the... (answered by scott8148)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the... (answered by nerdybill)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the... (answered by midwood_trail)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the... (answered by stanbon)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the... (answered by ankor@dixie-net.com)
Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 4... (answered by ankor@dixie-net.com)