A man rows at the rate of 5 mph in still water. If the river runs at t

Question

A man rows at the rate of 5 mph in still water. If the river runs at the rate of 1 mph, it takes him 1 hour to row to a place and come back. What is the total, upstream and downstream, distance covered by him in miles?

A) 2
B) 2.4
C) 2.8
D) 4
E) 4.8

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A) 2
B) 2.4
C) 2.8
D) 4
E) 4.8

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ShankSouljaBoi · Answer

D/5+1 + D/5-1 = 1
Answer = 2D = 24/5 = E

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rvgmat12 · Answer

x/6+x/4 = 1

x = 12/5 = 2.4

Total distance covered = 2.4*2 = 4.8

E

chetan2u · Answer

Logical 
The speed upstream will be 5-1 and downstream will be 5+1. 
If the entire route was traveled at the lesser speed, the distance would be 4 miles in 1 hour. But the speed for half the distance is 6mph, so surely the distance is more than 4.
Only 4.8 possible

Average speed 
Since the distance is traveled in exactly in 1 hour, we are looking at the average speed for entire distance. 
When distance traveled is same, the average speed = \frac{2*6*4}{6+4}=4.8

Algebraic 
Let the distance traveled one way be d, then time taken =  \frac{d}{4}+\frac{d}{6}=1……d=2.4 
Total distance =2d=2*2.4=4.8 miles

E

Archit3110 · Answer

still water speed = 5mph
upstream speed = 4mph
downstream = 6mph
we need to find avg speed
2 *6*4 / (6+4) = 48/10 ; 4.8
option E

GMATWhizTeam · Answer

Solution:

To be able to solve this question. we need to be aware of one fact/property:

If the speed of the boat in still water = x and the speed of the stream is y.

Then  speed of the boat upstream  = x-y   and  speed of the boat downstream  = x+y  .

We are given speed of boat in still water  = 5mph  and speed of river/stream  = 1mph .

Thus speed of the boat upstream  = 5-1=4mph  and speed of the boat downstream  = 5+1=6mph

Let the distance travelled be  D . So, distance travelled upstream and downstream  =\frac{D}{2}  respectively.

We are given the time of total journey  = 1hour

So. we can write  \frac{D}{2	imes 4} + \frac{D}{2	imes 6} = 1

⇒ \frac{D}{8} + \frac{D}{12} = 1

⇒ \frac{3D+2D}{24} = 1

⇒ D=\frac{24}{5}=4.8

Hence the right answer is  Option E .

Fdambro294 · Answer

The speed traveling against the current is = (5 - 1) = 4 mph

The speed traveling WITH the current is = (5 + 1) = 6 mph

In both cases we have a constant distance for each leg of the journey.

Over a constant distance, the Ratio of Speeds is Inversely Proportional to the Ratio of Time traveled

Speed UP : Speed DOWN = 4 : 6 = 2 : 3

Time spent traveling UP : Time spent traveling DOWN = 3 : 2

(3/5) of the Total Time is spent traveling at 4 mph

(2/5) of the Total Time is spent traveling at 6 mph

Total time is 1 hour

Leg 1: (4 mph) * (3/5 hr) = 12/5 miles

Leg 2: (6 mph) * (2/5 hr) = 12/5 miles

Total distance = 24/5 =

4.8 miles

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PolarisTestPrep · Answer

Hey guys,

Start with the standard formula for distance, rate, and time:

Disance = Rate * Time

Time = \frac{Distance}{Rate}

Total Time = Time to go upstream + Time to go downstream = 1 hour

Time to go upstream =  \frac{D}{4mph}

Time to go downstream =  \frac{D}{6mph}

Total Time = 1 =  \frac{D}{4mph}  +  \frac{D}{6mph}

1 =  \frac{3D}{12}  +  \frac{2D}{12}

1 =  \frac{5D}{12}

5D = 12

D =  \frac{12}{5}

A little long division gives you the answer:

The distance was 2.4 miles

Since he went upstream and downstream, the total distance is 2D

2.4 * 2 = 4.8

The answer is E

shisingh · Answer

Speed upstream ( against current ) = 5-1 = 4m/h
Speed downstream ( with current ) = 5+1 = 6m/h
Distance travelled is same x in both scenarios. 
total distance = 2x
Let time be t when upstream and 1-t when downstream so that total time is 1 hour.

Upstream : x = 4t
Downstream : x = 6(1-t)

Solving both gives, x = 12/5 and total distance is 24/5 =4.8m

A man rows at the rate of 5 mph in still water. If the river runs at t

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A man rows at the rate of 5 mph in still water. If the river runs at t

Prep Toolkit

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