The distance between Omaha and Lincoln...

[BTGmoderatorLU]

The distance between Omaha and Lincoln is 50 miles. Justin drives a car that gets 30 miles per gallon of gas, and Kayla drives a car that gets 20 miles per gallon. How many more gallons of gas does Kayla use on a round trip from Omaha to Lincoln?

A. 1
B. 1 2/3
C. 2 2/3
D. 3
E. 5

The OA is B.

I'm confused with this PS question. Experts, any suggestion? I'm not sure why that is the correct question. Thanks in advance.

[ErikaPrepScholar]

First, let's find how many gallons of gas each person uses on a round trip.

We know that the distance from Omaha to Lincoln is 50 miles. Since they're doing a round trip, they are going twice that distance - 50 miles from Omaha to Lincoln and then 50 miles from Lincoln back to Omaha. This gives a 100 mile trip in total.

Justin gets 30 miles per gallon of gas - in other words, he uses 1 gallon every 30 miles. So in a 100 mile trip, he uses
$$100\ miles\ \cdot\frac{1\ gallon}{30\ miles}=\frac{10}{3}\ gallons=3\frac{1}{3}\ gallons$$

Kayla gets 20 miles per gallon of gas - in other words, she uses 1 gallon every 20 miles. So in a 100 mile trip, she uses
$$100\ miles\ \cdot\frac{1\ gallon}{20\ miles}=5\ gallons$$

To find how many more gallons Kayla used than Justin, we can subtract the number of gallons Justin used from the number of gallons Kayla used
$$5\ gallons\ -\ 3\frac{1}{3}\ gallons\ =\ 1\frac{2}{3}\ gallons$$

This gives us the correct answer, B.

[EconomistGMATTutor]

The distance between Omaha and Lincoln is 50 miles. Justin drives a car that gets 30 miles per gallon of gas, and Kayla drives a car that gets 20 miles per gallon. How many more gallons of gas does Kayla use on a round trip from Omaha to Lincoln?

A. 1
B. 1 2/3
C. 2 2/3
D. 3
E. 5

The OA is B.

I'm confused with this PS question. Experts, any suggestion? I'm not sure why that is the correct question. Thanks in advance.

Hi LUANDATO,
Let's take a look at your question.

The distance between Omaha and Lincoln is 50 miles, therefore, to take a round trip Justin and Kayla have to cover a distance of 100 miles.
Justin drives a car that gets 30 miles per gallon of gas, Let's find the number of gallons it consumes for 100 miles.

For 30 miles Jason's car consumes gas = 1 gallon
For 1 mile Jason's car consumes gas = 1/30 gallon
For 100 miles Jason's car consumes gas = 100 * (1/30) gallons = 100/30 = 10/3 gallons

Similarly, we will find the number of gallons Kayla's car consumes for covering a distance of 100 miles.

For 20 miles Kayla's car consumes gas = 1 gallon
For 1 mile Kayla's car consumes gas = 1/20 gallon
For 100 miles Kayla's car consumes gas = 100 * (1/20) gallons = 100/20 = 5 gallons

We are asked to find how many more gallons of gas does Kayla use on a round trip from Omaha to Lincoln, so we will subtract the consumption of both the cars.
$$=\ 5-\frac{10}{3}$$
$$=\ \frac{15-10}{3}$$ $$=\ \frac{15-10}{3}=\frac{5}{3}=1\ \frac{2}{3}\ gallons$$

Therefore, Option B is correct.

Hope it helps.
I am available if you'd like any follow up.

[Scott@TargetTestPrep]

The distance between Omaha and Lincoln is 50 miles. Justin drives a car that gets 30 miles per gallon of gas, and Kayla drives a car that gets 20 miles per gallon. How many more gallons of gas does Kayla use on a round trip from Omaha to Lincoln?

A. 1
B. 1 2/3
C. 2 2/3
D. 3
E. 5

On a round trip from Omaha to Lincoln Justin uses 100/30 = 10/3 = 3 1/3 gallons, and Kayla uses 100/20 = 5 gallons. Thus, Kaylar uses 1 2/3 more gallons of gas.

Answer: B