Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

A certain car averages 25 miles per gallon of gasoline when [#permalink]

Show Tags

13 Jun 2009, 14:04

5

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

85% (hard)

Question Stats:

57% (03:05) correct
43% (02:06) wrong based on 255 sessions

HideShow timer Statistics

A certain car averages 25 miles per gallon of gasoline when driven in the city and 40 miles per gallon when driving on the highway. According to these rates, which of the following is closest to the number of miles per gallon that the car averages when it is driven 10 miles in the city and then 50 miles on the highway?

D. City - 25 miles in 1 gallon 1 miles in 1/25 gallon or .04 gallons. 10 miles in .04*10 = .4 gallons

Highway - 40 miles in 1 gallon.

gas consumed by car = .4(for city) + 1(for highway) = 1.4 gallons distance travelled = 50 miles so avearge/gallon = 50/1.4 = 35.7

I think it should be 1.25 gallons for the 50 miles on the highway, so total of 60 miles in 1.65 gallons, with approx. 36.36 miles / gallon output. The answer doesn't change however.

simple avg problem 40 miles ----- 1 G therefore 1 mile = 1/40 G so for 50 miles (1/40) 50= 5/4 G similerly 25 miles = 1G therefore 1 mile = 1/25 g so 10 miles= (1/25)*10 = 2/5 now total distance = 60 mile hence the avg = 60/((5/4) + (2/5)) hence 36 ans

Here is my reasoning and please feel free to correct me if im wrong.

the formula is (weight1)(datapoint1) + (weight2) (data point2) / sum of weights.

Weight 1 = 25 Weight 2= 40

Datapoint 1= 10 Data point 2= 50

25*10 + 40*50/ ( 25+40)

250+2000/65 2250/65 =36.5

D

Actually, you need to find the average miles/gallon so your 'datapoints' will be 25 and 40 miles/gallon. Weights will be the number of gallons in each case, not number of miles so 10 and 50 are not even the weights. If you get confused when deciding what the weights will be, just look at the denominator of the units of the quantity you are averaging. Since you want to find the average miles/gallon, your weights should be 'gallons' (because average miles/gallon will be total miles/total gallons... the formula has 'sum of weights' as the denominator so 'sum of weights' should be 'total gallons') Number of gallons used in each case = 10/25 and 50/40

Now you can use the formula: [25*(10/25) + 40*(50/40)]/[10/25 + 50/40] = 36.36 miles/gallon
_________________

Here is my reasoning and please feel free to correct me if im wrong.

the formula is (weight1)(datapoint1) + (weight2) (data point2) / sum of weights.

Weight 1 = 25 Weight 2= 40

Datapoint 1= 10 Data point 2= 50

25*10 + 40*50/ ( 25+40)

250+2000/65 2250/65 =36.5

D

Actually, you need to find the average miles/gallon so your 'datapoints' will be 25 and 40 miles/gallon. Weights will be the number of gallons in each case, not number of miles so 10 and 50 are not even the weights. If you get confused when deciding what the weights will be, just look at the denominator of the units of the quantity you are averaging. Since you want to find the average miles/gallon, your weights should be 'gallons' (because average miles/gallon will be total miles/total gallons... the formula has 'sum of weights' as the denominator so 'sum of weights' should be 'total gallons') Number of gallons used in each case = 10/25 and 50/40

Now you can use the formula: [25*(10/25) + 40*(50/40)]/[10/25 + 50/40] = 36.36 miles/gallon

Here is my reasoning and please feel free to correct me if im wrong.

the formula is (weight1)(datapoint1) + (weight2) (data point2) / sum of weights.

Weight 1 = 25 Weight 2= 40

Datapoint 1= 10 Data point 2= 50

25*10 + 40*50/ ( 25+40)

250+2000/65 2250/65 =36.5

D

Actually, you need to find the average miles/gallon so your 'datapoints' will be 25 and 40 miles/gallon. Weights will be the number of gallons in each case, not number of miles so 10 and 50 are not even the weights. If you get confused when deciding what the weights will be, just look at the denominator of the units of the quantity you are averaging. Since you want to find the average miles/gallon, your weights should be 'gallons' (because average miles/gallon will be total miles/total gallons... the formula has 'sum of weights' as the denominator so 'sum of weights' should be 'total gallons') Number of gallons used in each case = 10/25 and 50/40

Now you can use the formula: [25*(10/25) + 40*(50/40)]/[10/25 + 50/40] = 36.36 miles/gallon

Hi Karishma, Was wondering if I can ue the following approach city mileage = 25 now we are going 10 miles = 40%

Here is my reasoning and please feel free to correct me if im wrong.

the formula is (weight1)(datapoint1) + (weight2) (data point2) / sum of weights.

Weight 1 = 25 Weight 2= 40

Datapoint 1= 10 Data point 2= 50

25*10 + 40*50/ ( 25+40)

250+2000/65 2250/65 =36.5

D

Actually, you need to find the average miles/gallon so your 'datapoints' will be 25 and 40 miles/gallon. Weights will be the number of gallons in each case, not number of miles so 10 and 50 are not even the weights. If you get confused when deciding what the weights will be, just look at the denominator of the units of the quantity you are averaging. Since you want to find the average miles/gallon, your weights should be 'gallons' (because average miles/gallon will be total miles/total gallons... the formula has 'sum of weights' as the denominator so 'sum of weights' should be 'total gallons') Number of gallons used in each case = 10/25 and 50/40

Now you can use the formula: [25*(10/25) + 40*(50/40)]/[10/25 + 50/40] = 36.36 miles/gallon

Hi Karishma, Was wondering if I can ue the following approach city mileage = 25 now we are going 10 miles = 40%

highway = 40 now = 50 = 125% total mileage =

(10+50)/165% = 36.36

Thanks Sudhir

Yes, this is fine but make sure you use the units so that you know exactly what you are doing. The following is what I mean:

city mileage = 25 miles/gallon now we are going 10 miles = 40% = 0.4 gallons used

highway mileage = 40 miles/gallon now 50 miles = 125% = 1.25 gallons used

total mileage = Total Distance / Total amount of fuel used (10+50) miles/1.65 gallons = 36.36 miles/gallon
_________________

Re: A certain car averages 25 miles per gallon of gasoline when [#permalink]

Show Tags

09 Sep 2016, 12:05

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

A certain car averages 25 miles per gallon of gasoline when [#permalink]

Show Tags

09 Sep 2016, 14:38

A certain car averages 25 miles per gallon of gasoline when driven in the city and 40 miles per gallon when driving on the highway. According to these rates, which of the following is closest to the number of miles per gallon that the car averages when it is driven 10 miles in the city and then 50 miles on the highway?

A. 28 B. 30 C. 33 D. 36 E. 38

10*1/25 gpm+50*1/40 gpm=1.65 total gallons 60 total miles/1.65 total gallons=36.4 average mpg D. 36

gmatclubot

A certain car averages 25 miles per gallon of gasoline when
[#permalink]
09 Sep 2016, 14:38

It’s quickly approaching two years since I last wrote anything on this blog. A lot has happened since then. When I last posted, I had just gotten back from...

Since my last post, I’ve got the interview decisions for the other two business schools I applied to: Denied by Wharton and Invited to Interview with Stanford. It all...