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

 It is currently 25 Mar 2019, 11:13

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 certain road trip was completed in two parts interrupted by an hour-

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 53831
A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

26 Apr 2017, 08:17
1
2
00:00

Difficulty:

25% (medium)

Question Stats:

80% (02:36) correct 20% (03:10) wrong based on 122 sessions

HideShow timer Statistics

A certain road trip was completed in two parts interrupted by an hour-long lunch break. During the first portion of the trip the average speed was 55 miles per hour and the average speed during the second part of the trip was 63 miles per hour. If the trip was 480 miles long and took a total of 9 hours then which of the following is the amount of time spent driving before the lunch break?

A. 2
B. 3
C. 4
D. 5
E. 6

_________________
Senior Manager
Joined: 24 Apr 2016
Posts: 331
Re: A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

26 Apr 2017, 10:42
Let distance travelled during the First Part = F
Let distance travelled during the Second Part = S

F+S = 480 --- (i)

Time Taken to complete First Part = F/55
Time Taken to complete Second Part = S/63

Total Time Taken excluding the hour-long lunch break = F/55 + S/63 = 9-1 = 8

(63F+55S)/55*63 = 8

63F+55S = 27720 --- (ii)

55F+55S = 26400
63F+55S = 27720

8F = 1320
F = 165

The amount of time spent driving before the lunch break = 165/55 = 3 hours

Answer is B. 3
VP
Joined: 07 Dec 2014
Posts: 1161
A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

26 Apr 2017, 11:48
1
1
Bunuel wrote:
A certain road trip was completed in two parts interrupted by an hour-long lunch break. During the first portion of the trip the average speed was 55 miles per hour and the average speed during the second part of the trip was 63 miles per hour. If the trip was 480 miles long and took a total of 9 hours then which of the following is the amount of time spent driving before the lunch break?

A. 2
B. 3
C. 4
D. 5
E. 6

let d=pre-break distance
d/55+(480-d)/63=8 hours
d=165 miles
165 miles/55 mph=3 hours
B
Intern
Joined: 01 Jul 2018
Posts: 1
Re: A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

26 Jul 2018, 22:27
1
The trip actually took 8 hours of driving time excluding the one hour break.

Let x and y be the number of hours when the average speeds were 55 miles per hour and 63 miles per hour.
Hence,
Using Distance = Speed x Time, we can write :
x + y = 8
and
55x + 63y = 480 (Total Distance travelled)
Solving these equations gives the value of x to be 3 hours.
Manager
Joined: 23 Nov 2017
Posts: 120
Location: Singapore
Concentration: Strategy, Other
GMAT 1: 660 Q49 V33
Re: A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

26 Jul 2018, 23:24
2
I did this by weighted average method.

total distance = 480
total time taken =8
average speed = 480/8 =60

by allegation method;
55 63
\ /
60
/ \
3 5

The ratio I get is part 1: part2 = 3:5

I split the total time like wise =3/8 * 8 hrs = 3 hrs.

hit kudos if that helped.
Intern
Joined: 27 Feb 2018
Posts: 36
Location: India
WE: Engineering (Real Estate)
Re: A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

27 Jul 2018, 00:31
Bunuel wrote:
A certain road trip was completed in two parts interrupted by an hour-long lunch break. During the first portion of the trip the average speed was 55 miles per hour and the average speed during the second part of the trip was 63 miles per hour. If the trip was 480 miles long and took a total of 9 hours then which of the following is the amount of time spent driving before the lunch break?

A. 2
B. 3
C. 4
D. 5
E. 6

Guys, I got an interesting solution, I solved it in under 30 seconds. Just by looking at the speeds and the total distance.
Given Speed 1 = 55 mph & Speed 2 = 63 mph
The options given are all whole numbers, so 55*x + 63*y = 480 miles. We need to find "x"
In order for x to be whole number, y can be only 5 because its the only number between 1 and 9 which gives possible multiple of 55.
So then if y=5, then x=9-5-1=3
So, B is the answer in 30 sec
Manager
Joined: 19 Nov 2017
Posts: 177
Location: India
Schools: ISB
GMAT 1: 670 Q49 V32
GPA: 4
Re: A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

27 Jul 2018, 01:09
1
Attachment:

Q.png [ 11.25 KiB | Viewed 627 times ]
I chose a different way to do this question because the normal way required some time consuming calculations.

I used the options to find the answer

Average speed of first half 55, and average speed of second half 63.
Total distance is 480 (units digit is 0)

Units digit of 55*option + 63*(8 - option) should be 0. (because D = S*T)
_________________
Regards,

Vaibhav

Sky is the limit. 800 is the limit.

~GMAC
Manager
Joined: 16 May 2017
Posts: 51
GPA: 3.8
WE: Medicine and Health (Health Care)
Re: A certain road trip was completed in two parts interrupted by an hour-  [#permalink]

Show Tags

20 Oct 2018, 04:11
Average speed before lunch-break=55 mph
Average speed after lunch-break=63 mph

Lunch break= 1hr
So, actual time taken for the trip= 9-1= 8 hr

Let time taken before lunch-break=x
Let time taken before lunch-break=8-x

So total distance: 55x+63(8-x)=480, x=3 hrs.

Ans(B)
Re: A certain road trip was completed in two parts interrupted by an hour-   [#permalink] 20 Oct 2018, 04:11
Display posts from previous: Sort by

A certain road trip was completed in two parts interrupted by an hour-

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.