A motorist passing through an unfamiliar city needs to fill her car's

­A motorist passing through an unfamiliar city needs to fill her car's fuel tank soon, well before she leaves the city, and needs to minimize her expenses. Nearby is the King Petrol station, offering the correct fuel for 2.00 euroes per liter. She has seen about one petrol station ever 2 kilometers (km) of driving, on average, though distances vary. Prices at different petrol stations appear to vary randomly by up to 10%; roughly 2 km behind her in her journey she saw the correct fuel for 1.81 euros per liter. The fuel efficiency of her car under the current driving conditions is about 10 liters per 100 km. She could get a small amout of fuel at one station to allow her to drive to another station within the city.

On the basis of the information in the passage, select for "Reason to stop" the factor that most clearly provides a logical reason for the motorist to stop at the King Petrol station. And select for "Reason not to stop" the factor that most clearly provides a logical reason for the motorist not to stop at the King Petrol station. Make only two selections, one in each column.

Given what the passage says, we can get the impression that a reason for her to stop is to get a little fuel and that a reason for her not to stop is to hold out for a better price, but we'll see what the choices say.

Differences in prices between fuel in the city and in the surrounding area

Since the passage says that the motorist "needs to fill her car's fuel tank soon, well before she leaves the city," the difference between prices in the city and prices in the surrounding areas does not affect her decision. After all, she cannot wait for the prices in the surrounding areas.

So, this choice is irrelevant.

Eliminate.

The option of getting a small amount of fuel

Of all the choices, this is the only one that provides any reason to stop.

We can eliminate all the others except The observed fuel prices as basically irrelevant, and The observed fuel prices are clearly not a reason to stop since she has seen lower prices at other stations.

Select for Reason to stop.

The distance from this city to the next

Since the passage says that the motorist "needs to fill her car's fuel tank soon, well before she leaves the city," the distance from this city to the next does not affect her decision. After all, she cannot wait to get fuel in the next city.

So, this choice is irrelevant.

Eliminate.

The car's fuel efficiency

I had a hard time eliminating this choice because, since we have the average distance between stations, knowing that she can go 10 kilometers on a liter of fuel could seem to help us determine whether it makes sense to stop or wait and see whether she can get to another station with a lower price before she runs out of fuel.

Here's the issue though.

The car's fuel efficiency could affect the motorist's decision regarding whether to stop or wait IF we knew how much fuel she has. However, the fuel efficiency alone does not indicate whether she should stop or not stop. After all, we already know that she needs to stop soon, but without knowing how much fuel she has, we don't know how soon even with information about the fuel efficiency.

Eliminate.

The observed fuel prices

The passage says the following:

So, "the observed fuel prices" include the currently available price of 2.00 and other prices as low as around 1.80.

So, by waiting, she'll likely get a lower price within perhaps 2 to 10 kilometers.

Thus, the observed fuel prices indicate that not stopping could help her to "minimze her expenses."

Select for Reason not to stop.

Correct answer: The option of getting a small amount of fuel, The observed fuel prices­