rate against the current = 10-5 = 5 mph
rate with the current = 10+5 = 15 mph
let the distance be x
time against the current = x/5
time with the current = x/15
x/5 - x/15 = 4
times 15
3x - x = 60
2x = 60
x = 30
each way is 30 miles
time upstream = 30/5 = 6 hrs
time downstream = 30/15 = 2 hrs
(note the difference is 4 hrs, as it should be)
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.
please help/ thank you.
1 answer
3 answers