Question 1008571: Kate can row a boat 10 miles per hour in still water. in a river where the current is 5 miler per hour, it take her 4 hour longer to row a given distance upstream than to travel the same distance downstream. Find how long it takes her to row upstream, how long to row downstream, and how many miles she rows.
solve:
upstream data :
rate: 10-5=5 mph; distance = x miles, time = x/5 mph
down stream data
rate =10+5=15 mph; distance = x miles; time = x/15 mph
equation:
x/5 + x/15 = 4 hrs
3x + x =60
4x=60
x = 15 miles (distance)
time upstream: 15/5=3hrs
time downstream: 15/15= h hours
But these result show different number in hint solution.
Hint solution show is down stream is 2 hrs.
upstream is 6 hrs.
60 miles roundtrip.
please help me show how to get these answer show in the Hint solution. i don't know how get it . Thank you.
Answer by josgarithmetic(39618)   (Show Source):
You can put this solution on YOUR website! This type of example was analyzed in another very recent help request. Go to that one and study it. The strategy can be this:
Assign variables to all numbers, both known and unknown.
Arrange a data table.
Form a system of equations.
Solve the system.
The basic concept is travel rates in the fact, RT=D to relate rate, time, distance. The data table should be of this form:
RATE TIME DISTANCE
UPSTREAM () () ()
DOWNSTREAM () () ()
No different from the other exercise problem ; just different given values.
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