Problema Solution
A boat's crew rowed 20 miles downstream, with the current, in 2 hours. The return trip upstream, against the current, covered the same distance, but took 5 hours. Find the crew's rowing rate in still water and the rate of the current.
Answer provided by our tutors
boat rate in still water = x
current rate = y
...
Rate
upstream = x-y
downstream = x+y
..
time downstream = time upstream
...
t=d/r
20/(x+y)=2
multiply by (x+y)
20=2(x+y)
/2
10=x+y
x+y=10.................1
..
20/(x-y)=5
20=5(x-y)
/5
4=x-y
x-y =4..................2
...
add 1 & 2
2x=14
/2
x=7mph boat rate in still water.
y=3mph rate of current