A boat can travel 24 mph in still water. If it travels 186 miles with the current in the same length of time it travels 102 miles against the current, what is t

Question

A boat can travel 24 mph in still water. If it travels 186 miles with the current in the same length of time it travels 102 miles against the current, what is the speed of the current?

Answer 1

a = still water movement and b = current's effect on movement

Let's start by using the elimination method:

a + b = 186 miles in x hours

a - b = 102 miles in x hours

----------------

2a = 288 miles in x hours

a = 144 miles in x hours

 

In other words, if the water is still, the boat travels 144 miles in the given time x.

Now to find the current's effect (b):

144 + b = 186

b = 42

 

check:

144 - 42 = 102

102 = 102

 

Now take the still water travel distance and divide by its speed to find out how long it traveled:

144 miles / 24 mph = 6 hours traveled

So the given time is 6 hours.

 

42 miles affected by the current ÷ 6 hours = 7 mph for the current.