Julie powers is a long distance swimmer.She can swim 4 mph in still water.she takes as long to swim 8 miles upstream as 24 miles downstream.how fast is it?

Question

Hard!please help.find how fast the current is.

Answer 1

Distance = Rate times Time  

 

Let C be the speed of the current  

 

Then she swims at (4 - C) mph upstream  

and she swims at (4 + C) mph downstream  

 

Let T be the time (same in both cases)  

 

 8  = (4 - C)*T = 4*T - C*T  is the upstream equation  

24 = (4 + C)*T = 4*T + C*T is the downstream equation  

 

Add these 2 equations together to get  

 

32 = 8*T 

T = 4  

 

Plug this value for T in to the 1st equation and solve for C  

 

8 = (4 - C)*4

2 = 4 - C

C = 2 mph is the speed of the current  

 

Check:  Upstream distance = (4 - 2)*4 = 8 miles

           Downstream distance = (4 + 2)*4 = 24 miles