sandy wrote:

Attachment:

#GREpracticequestion If s is a speed, in miles per hour, at which the energy.jpg

If s is a speed, in miles per hour, at which the energy used per meter during running is twice the energy used per meter during walking, then, according

to the graph above, s is between

A 2.5 and 3.0

B 3.0 and 3.5

C 3.5 and 4.0

D 4.0 and 4.5

E 4.5 and 5.0

Let's first familiarize ourselves with this diagram.

We'll start by examining what happens when

runners and

walkers travel at a speed of 4 miles per hour

The location of the

blue dot tells us that people RUNNING 4 mph use about

270 joules per metre

The location of the

red dot tells us that people WALKING 4 mph use about

190 joules per metre

270/

190 ≈ 1.4

So, when travelling at a speed of 4 mph, runners use about

1.4 times the energy that walkers use while travelling at a speed of 4 mph

We're looking for a speed at which runners use

TWICE the energy that walkers use while travelling at the same speed.

So we'll keep looking...

Now let's examine what happens when

runners and

walkers travel at a speed of approximately 2.7 miles per hour

The location of the

blue dot tells us that people RUNNING 2.7 mph use about

290 joules per metre

The location of the

red dot tells us that people WALKING 2.7 mph use about

145 joules per metre

290/

145 ≈ 2

So, when travelling at a speed of 2.7 mph, runners use about

2 times the energy that walkers use while travelling at a speed of 2.7 mph

Answer: A

Cheers,

Brent

_________________

Brent Hanneson – Creator of greenlighttestprep.com

Sign up for my free GRE Question of the Day emails