Asked by mindy
A boat traveled 45 miles downstream (w/ the current) in 3 hours and made the return trop (against the current) in 5 hours. What was the speed of the boat and what was the speed of the current?
Answers
Answered by
MathMate
b=boat (mph)
c=current (mph)
Set up equations using distance=speed*time
3(b+c)=45 ...(1)
5(b-c)=45 ...(2)
Multiply (1) by 5 and (2) by 3:
15b+15c = 225 ...(1a)
15b-15c = 135 ...(2a)
Add (1a) and (2a)
30b+0 = 360
b = 360/30 = 12
Subtract (2a) from (1a)
0+30c = 90
c = 90/30 = 3
Boat speed is 12 mph,
current speed is 3 mph
c=current (mph)
Set up equations using distance=speed*time
3(b+c)=45 ...(1)
5(b-c)=45 ...(2)
Multiply (1) by 5 and (2) by 3:
15b+15c = 225 ...(1a)
15b-15c = 135 ...(2a)
Add (1a) and (2a)
30b+0 = 360
b = 360/30 = 12
Subtract (2a) from (1a)
0+30c = 90
c = 90/30 = 3
Boat speed is 12 mph,
current speed is 3 mph
Answered by
Reiny
speed of boat ---- x mph
speed of current -- y mph
then :
1. 3(x+y) = 45 or x+y = 15
2. 5(x-y) = 45 or x-y = 9
add them:
2x = 24
x = 12
from one of the others, y = 3
etc.
speed of current -- y mph
then :
1. 3(x+y) = 45 or x+y = 15
2. 5(x-y) = 45 or x-y = 9
add them:
2x = 24
x = 12
from one of the others, y = 3
etc.
Answered by
mindy
thank you guys so much
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.