Last visit was: 21 May 2024, 02:47 It is currently 21 May 2024, 02:47
Close
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
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.
Close
Request Expert Reply
Confirm Cancel
SORT BY:
Date
Tags:
Show Tags
Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 93365
Own Kudos [?]: 625460 [16]
Given Kudos: 81917
Send PM
avatar
Intern
Intern
Joined: 07 Jun 2015
Posts: 6
Own Kudos [?]: 6 [3]
Given Kudos: 25
Send PM
GMAT Club Legend
GMAT Club Legend
Joined: 03 Oct 2013
Affiliations: CrackVerbal
Posts: 4944
Own Kudos [?]: 7675 [1]
Given Kudos: 216
Location: India
Send PM
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 10152
Own Kudos [?]: 16709 [2]
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Send PM
Re: The time it took car P to travel 600 miles was 2 hours less than the [#permalink]
2
Kudos
Expert Reply
Rather than going for assuming speed to be 'x', try doing by hit n trial.

1st chance: (Assume)Time taken by R = 12 hours

Distance: 600 miles.

Speed: 50 miles per hour.

Therfore, Time taken by P = 12 - 2 = 10 hours
Distance: 600 miles.

Speed: 60 miles per hour.

Car P’s average speed was 10 miles per hour greater than that of car R - Proved.


2nd chance: Try with options.

Suppose we pick option D.
But try taking the option that divides 600 completely. So, try taking 60.

R = 60 miles per hour - Distance = 600 - Time taken = 10 hour.
P = 60+10 = 70 miles per hour - Distance = 600 - Time taken = 9.x hour (not 2 hours less than R).


Answer B
Manager
Manager
Joined: 04 May 2020
Posts: 119
Own Kudos [?]: 17 [0]
Given Kudos: 25
Location: Italy
Schools: IESE'23
Send PM
Re: The time it took car P to travel 600 miles was 2 hours less than the [#permalink]
I tried with options
I usually start picking B out. I know that:

R: Avg: y Time: x Distance: 600
P: Avg: y+10 Time: x-2 Distance: 600
If i try with answer B, i get:
R: Avg: 50 Time: 12 Distance: 600
P: Avg: 60 Time: 10 Distance: 600
YES!

Answer -> B
Intern
Intern
Joined: 28 Jun 2020
Posts: 6
Own Kudos [?]: 3 [0]
Given Kudos: 11
Send PM
The time it took car P to travel 600 miles was 2 hours less than the [#permalink]
Bunuel wrote:
The time it took car P to travel 600 miles was 2 hours less than the time it took car R to travel the same distance. If car P’s average speed was 10 miles per hour greater than that of car R, what was car R’s average speed, in miles per hour?

A. 40
B. 50
C. 60
D. 70
E. 80


I always get confused with these types of problems. So here's another approach. It's a little lengthy but easy!
Since, the numbers are very simple, the calculations should not take a lot of time! :)
Let's use the options:
A: If Speed of R= 40 mph
then time taken will be, t=d/s
t= 600/40= 15 hours

Now, we know, that P(t)= t-2= 13
And P(s)= s+10= 50 mph
D= s*t and we know D=600 miles
So, now, D= 13*50= 650 miles
Not our answer

B: R=50 mph
t= 600/50= 12hours
Now, P(t)= 10 hours
S= 60 mph
D= 60*10= 600 miles
CORRECT

Hence, Speed for R should be 50 mph
Correct answer is B.
Target Test Prep Representative
Joined: 14 Oct 2015
Status:Founder & CEO
Affiliations: Target Test Prep
Posts: 18874
Own Kudos [?]: 22278 [0]
Given Kudos: 285
Location: United States (CA)
Send PM
Re: The time it took car P to travel 600 miles was 2 hours less than the [#permalink]
Expert Reply
Bunuel wrote:
The time it took car P to travel 600 miles was 2 hours less than the time it took car R to travel the same distance. If car P’s average speed was 10 miles per hour greater than that of car R, what was car R’s average speed, in miles per hour?

A. 40
B. 50
C. 60
D. 70
E. 80

Solution:

Since the answer choices are easy numbers, let’s solve the problem numerically instead of algebraically. That is, we can check each answer choice until we find the correct answer.

If car R’s speed is 40 mph, then car P’s speed is 50 mph. Furthermore, it will take car R 600/40 = 15 hours and car P 600/50 = 12 hours to travel 600 miles. However, since 12 is not 2 less than 15, we see that choice A is not the correct answer.

If car R’s speed is 50 mph, then car P’s speed is 60 mph. Furthermore, it will take car R 600/50 = 12 hours and car P 600/60 = 10 hours to travel 600 miles. However, since 10 is 2 less than 12, we see that choice B is the correct answer.

Answer: B
User avatar
Non-Human User
Joined: 09 Sep 2013
Posts: 33131
Own Kudos [?]: 828 [0]
Given Kudos: 0
Send PM
Re: The time it took car P to travel 600 miles was 2 hours less than the [#permalink]
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.
GMAT Club Bot
Re: The time it took car P to travel 600 miles was 2 hours less than the [#permalink]
Moderator:
Math Expert
93364 posts