It is currently 22 Feb 2019, 16:23

### 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

# Susan travels by car at an average speed of 50 miles per

 Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
GRE Prep Club Legend
Joined: 07 Jun 2014
Posts: 4856
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 102

Kudos [?]: 1742 [0], given: 397

Susan travels by car at an average speed of 50 miles per [#permalink]  24 Nov 2017, 20:39
Expert's post
00:00

Question Stats:

100% (00:16) correct 0% (00:00) wrong based on 11 sessions
Susan travels by car at an average speed of 50 miles per hour for 4 hours and then at an average speed of 20 miles per hour for 2 hours. What is her average speed, in miles per hour, for the entire 6-hour trip?

A. 25
B. 30
C. 35
D. 40
E. 45

Drill 1
Question: 4
Page: 521
[Reveal] Spoiler: OA

_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Director
Joined: 20 Apr 2016
Posts: 818
WE: Engineering (Energy and Utilities)
Followers: 9

Kudos [?]: 588 [0], given: 115

Re: Susan travels by car at an average speed of 50 miles per [#permalink]  02 Dec 2017, 10:55
sandy wrote:
Susan travels by car at an average speed of 50 miles per hour for 4 hours and then at an average speed of 20 miles per hour for 2 hours. What is her average speed, in miles per hour, for the entire 6-hour trip?

A. 25
B. 30
C. 35
D. 40
E. 45

Drill 1
Question: 4
Page: 521

Here in the first part,

Distance = speed * Time

Distance = 50 * 4 = 200 miles (Speed = 50 miles per hour ; Time = 4 hrs)

in the second part

Distance = 20 * 2 = 40 miles (Speed = 20 miles per hour ; Time = 2 hrs)

Therefore Total distance = 240 miles.

Av speed for the entire trip = 240/6 = 40 miles per hour (Since total time = 6 hrs)
_________________

If you found this post useful, please let me know by pressing the Kudos Button

Rules for Posting https://greprepclub.com/forum/rules-for ... -1083.html

GRE Prep Club Legend
Joined: 07 Jun 2014
Posts: 4856
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 102

Kudos [?]: 1742 [0], given: 397

Re: Susan travels by car at an average speed of 50 miles per [#permalink]  09 Dec 2017, 19:45
Expert's post
Explanation

Use the given averages to figure out Susan’s total distance: 4 hours at an average speed of 50 miles per hour is a total of 200 miles, and 2 hours at an average speed of 20 miles per hour is a total of 40 miles.

Susan goes a total of 240 miles in 6 hours, thus, her average speed is $$\frac{240}{6}$$ miles/hour, or 40 miles per hour.

The answer is choice D.
_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Intern
Joined: 24 Jan 2019
Posts: 27
Followers: 0

Kudos [?]: 2 [0], given: 29

Re: Susan travels by car at an average speed of 50 miles per [#permalink]  05 Feb 2019, 07:02
Why cant we use the avg speed equation in this problem? as when i tried it , it gave me a different answer.
Avg Speed = 2(S1.S2) / S1 + S2
And when is this equation applicable?

Thanks
Director
Joined: 20 Apr 2016
Posts: 818
WE: Engineering (Energy and Utilities)
Followers: 9

Kudos [?]: 588 [0], given: 115

Re: Susan travels by car at an average speed of 50 miles per [#permalink]  05 Feb 2019, 10:33
SKH121 wrote:
Why cant we use the avg speed equation in this problem? as when i tried it , it gave me a different answer.
Avg Speed = 2(S1.S2) / S1 + S2
And when is this equation applicable?

Thanks

That will be applicable when Distance travelled in first half = distance travelled in 2nd half
_________________

If you found this post useful, please let me know by pressing the Kudos Button

Rules for Posting https://greprepclub.com/forum/rules-for ... -1083.html

Re: Susan travels by car at an average speed of 50 miles per   [#permalink] 05 Feb 2019, 10:33
Display posts from previous: Sort by

# Susan travels by car at an average speed of 50 miles per

 Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.