Problema Solution
It takes a motor boat 4 hours to travel 56 miles down a river and 3 hours longer to make the return trip. Find the speed of the boat in still water and the speed of the current .
Answer provided by our tutors
Downstream,
Time = 4 hr ; distance = 56 miles ; rate = d/t = 56/4 = 14 mph
Upstream,
Time = 7 hr ; distance = 56 miles ; rate = d/t = 56/7 = 8 mph
Let boat speed be "b"; Let water speed be "w"
EQUATIONS:
b+w = 14
b-w = 8
Add to get:
2b = 22
b = 11 mph (boat speed in still water)
Substitute to get water speed:
11+w = 14
w = 3 mph (water speed)