Whitney left the library traveling 4 mph. Then, 2 hours later, Renee left traveling the same direction at 8 mph. How long until Renee catches up with Whitney?

Question

Whitney left the library traveling 4 mph. Then, 2 hours later, Renee left traveling the same direction at 8 mph. How long until Renee catches up with Whitney?

Answer 1

Let x= 1 hour and set them equal to each other

 

Whitney= 4+2x+x

Renee= 8+x

 

4+3x=8+x

2x=4

X=2

 

So after 2 hours Renee travels 16m  (8*2=16m), and since you add the 2 hours to Whitney's 2 hour head start:

 

4*(2+2)=16m

 

After 2 hours they both travel 16m.

 

 

Answer 2

Let x= time

 

Whitney is 4x

Renee is 8x but have to subtract the distance Whitney travelled in 2 hours

 

So 

 

Whitney= 8x-(4*2) or 8x-8

 

Now set them equal to each other to see when x (time) is equal but since we used a constant of 2 for Whitney (4*2) on one side of the equation, we cannot use a variable on the other side. So simply use 4 not 4x for Whitney

 

4=8x-8

4=8(x-1)

4/8=x-1

1/2=x-1

X 1+1/2= 3/2 or 1 1/2 hours

 

 

Answer 3

So first you need to figure out how long Whitney traveled in 2 hours.  4miles/hour times 2 hours equals 8 miles but Whitney is still moving at 4 miles per hour when Renee leaves the library so in the hour it took Renee to travel those 8 miles Whitney has moved another 4 miles.  So you need to set up an equation. 

 

if x is the number of hours that they have been traveling since Renee started moving:
Whitney travels 4x+8 miles and Renee travels 8x miles

 

we want to know when they both have traveled the same number of miles so we set those equal to each other.

 

4x+8=8x

-4x     -4x

8=4x

2=x

 

Renee travels for 2 hours before catching up with Whitney

Answer 4

You need to first find out how far Whitney traveled in  2 hours. For every hour she traveled 4 miles. If you multiply 4 miles by 2 hours you will get 8 miles. So Whitney already traveled 8 miles in 2 hours. Now how many hours would it take for Renee to travel 8 miles?