GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 20 Aug 2019, 16:13

### GMAT Club Daily Prep

#### 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

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

# A car travels from Town A to Town B at an average speed

Author Message
TAGS:

### Hide Tags

Manager
Joined: 28 May 2009
Posts: 144
Location: United States
Concentration: Strategy, General Management
GMAT Date: 03-22-2013
GPA: 3.57
WE: Information Technology (Consulting)
A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

05 Jan 2013, 18:08
1
7
00:00

Difficulty:

15% (low)

Question Stats:

79% (01:49) correct 21% (01:09) wrong based on 434 sessions

### HideShow timer Statistics

A car travels from Town A to Town B at an average speed of 40 miles per hour, and returns immediately along the same route at an average speed of 50 miles per hour. What is the average speed in miles per hour for the round-trip?

(A) $$45\frac{4}{9}$$ mph

(B) 44 mph

(C) 45 mph

(D) $$44\frac{4}{9}$$ mph

(E) $$44\frac{1}{9}$$ mph

_________________
Senior Manager
Joined: 27 Jun 2012
Posts: 359
Concentration: Strategy, Finance
Schools: Haas EWMBA '17
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

05 Jan 2013, 18:47
4
1
Using "Pick numbers" strategy, assume total distance as 200 miles. (LCM of 40 & 50)

Time taken to travel from A to B = 200/40 = 5 hours
Time taken to travel from B to A = 200/50 = 4 hours

$$Average(speed) = \frac{{Total (Distance) }}{{ Total (Time) }}= \frac{(200+200)}{(5+4)} = \frac{400}{9} = 44 \frac{4}{9}$$

Hence Choice(D).
_________________
Thanks,
Prashant Ponde

Tough 700+ Level RCs: Passage1 | Passage2 | Passage3 | Passage4 | Passage5 | Passage6 | Passage7
VOTE GMAT Practice Tests: Vote Here
PowerScore CR Bible - Official Guide 13 Questions Set Mapped: Click here
##### General Discussion
e-GMAT Representative
Joined: 02 Nov 2011
Posts: 2858
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

08 Jan 2013, 02:07
1
2
megafan wrote:
A car travels from Town A to Town B at an average speed of 40 miles per hour, and returns immediately along the same route at an average speed of 50 miles per hour. What is the average speed in miles per hour for the round-trip?

(A) $$45\frac{4}{9}$$ mph

(B) 44 mph

(C) 45 mph

(D) $$44\frac{4}{9}$$ mph

(E) $$44\frac{1}{9}$$ mph

Hi,

This is a classic question on Speed, time, & distance.

1. When time traveled in each segment is constant, then average speed is simple mean of speeds.

2. When distance traveled in each segment is constant, then average speed is reciprocal of simple mean of reciprocal of speeds. It is basically called Harmonic mean.

So this question falls in the category of 2.

=> So, average speed = Reciprocal of mean of reciprocals of 40 & 50.

=> Average speed = Reciprocal of mean of 1/40 & 1/50.

=> Average speed = Reciprocal of (1/40 + 1/50)/2 = Reciprocal of (5+4)/400 = 44 4/9 .

-Shalabh
_________________
SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1785
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

14 Jan 2015, 01:22
1
$$Average(speed) = \frac{{Total (Distance) }}{{ Total (Time)}}$$

Let the distance between Town A & Town B = 1

Setting up the equation:

Average speed $$= \frac{1+1}{\frac{1}{40} + \frac{1}{50}} = \frac{400}{9} = 44\frac{4}{9}$$
_________________
Kindly press "+1 Kudos" to appreciate
Manager
Joined: 22 Nov 2016
Posts: 205
Location: United States
GPA: 3.4
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

26 Jun 2017, 16:11
Pick a multiple of 40 and 50 as the distance. 200 is a good number.
Hence the average speed is 400/9 = 44 4/9, D
_________________
Kudosity killed the cat but your kudos can save it.
Director
Joined: 12 Nov 2016
Posts: 708
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: Q157 V158
GPA: 2.66
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

13 Aug 2017, 13:06
megafan wrote:
A car travels from Town A to Town B at an average speed of 40 miles per hour, and returns immediately along the same route at an average speed of 50 miles per hour. What is the average speed in miles per hour for the round-trip?

(A) $$45\frac{4}{9}$$ mph

(B) 44 mph

(C) 45 mph

(D) $$44\frac{4}{9}$$ mph

(E) $$44\frac{1}{9}$$ mph

This is really like an approximation question and round trip question jumbled into one. Anyways, because this is a round trip question the distances for both trips are the same... mathematically that means

distance 1 = 40 (t)
distance 2= 50 (t)

We can just plug in a random value like 200

200= 40t
t=5

200=50t
t=4

Total Distance= Avgspeed * Total Time
400= avgsped* 9
400/9= 44.4444444.. round to closet value

44 4/9

D
Intern
Joined: 29 May 2017
Posts: 2
Schools: Booth '20
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

24 Aug 2017, 22:11
A MOTOR TRAVEL WITH AN AVERAGE SPEED OF 49/HOUR FOR 3 HOURS THEN AN avreage speed of 99/ hour at spped of 39/ 2 hours
Retired Moderator
Status: The best is yet to come.....
Joined: 10 Mar 2013
Posts: 488
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

05 Dec 2017, 03:22
egmat wrote:
megafan wrote:
A car travels from Town A to Town B at an average speed of 40 miles per hour, and returns immediately along the same route at an average speed of 50 miles per hour. What is the average speed in miles per hour for the round-trip?

(A) $$45\frac{4}{9}$$ mph

(B) 44 mph

(C) 45 mph

(D) $$44\frac{4}{9}$$ mph

(E) $$44\frac{1}{9}$$ mph

Hi,

This is a classic question on Speed, time, & distance.

1. When time traveled in each segment is constant, then average speed is simple mean of speeds.

2. When distance traveled in each segment is constant, then average speed is reciprocal of simple mean of reciprocal of speeds. It is basically called Harmonic mean.

So this question falls in the category of 2.

=> So, average speed = Reciprocal of mean of reciprocals of 40 & 50.

=> Average speed = Reciprocal of mean of 1/40 & 1/50.

=> Average speed = Reciprocal of (1/40 + 1/50)/2 = Reciprocal of (5+4)/400 = 44 4/9 .

-Shalabh
When distance traveled in each segment is constant, then average speed simply be $$\frac{2xy}{x+y}$$, where x and y are speeds.$$\frac{2*40*50}{40+50}$$ = $$44\frac{4}{9}$$
_________________
Hasan Mahmud
Non-Human User
Joined: 09 Sep 2013
Posts: 12053
Re: A car travels from Town A to Town B at an average speed  [#permalink]

### Show Tags

01 Feb 2019, 03:57
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.
_________________
Re: A car travels from Town A to Town B at an average speed   [#permalink] 01 Feb 2019, 03:57
Display posts from previous: Sort by