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

It is currently 20 Apr 2019, 19:40

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

Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If

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

Hide Tags

 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 54376
Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If  [#permalink]

Show Tags

New post 23 Feb 2016, 03:00
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

95% (01:38) correct 5% (02:40) wrong based on 196 sessions

HideShow timer Statistics

Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If he then continued to ride at a different constant rate for another three hours, and at the end of the three hours his average speed for the entire five hour ride was 30mph, what was his average speed over the three hour portion of his ride?

A. 14 mph
B. 20 mph
C. 70/3 mph
D. 80/3 mph
E. 34 mph

Kudos for correct solution.

_________________
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7569
Re: Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If  [#permalink]

Show Tags

New post 23 Feb 2016, 09:47
1
Bunuel wrote:
Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If he then continued to ride at a different constant rate for another three hours, and at the end of the three hours his average speed for the entire five hour ride was 30mph, what was his average speed over the three hour portion of his ride?

A. 14 mph
B. 20 mph
C. 70/3 mph
D. 80/3 mph
E. 34 mph

Kudos for correct solution.


Hi,
there are various ways we could do the Q..

1) weighted average--
40 is higher and let x be the lower speed ... ratio of time for 40:x=2:3
since 30 is the average, 40 -3/5 * (40-x)=30..
so 3*8-3/5 x=10..
3/5 x=14 or x=70/3.. ans C


2) average method--
2 hrs at 40 and 3 hrs at x= 40*2+3x..
average= (80+3x)/5=30..
80+3x=150..
3x=70 or x=70/3..
C

3) POE--
If you do not know the method, you can get you rprob of correct answer to 1/2 from 1/5
since the average is 30, the answer has to be less than 30 so E is out..
If the time was only four hours, two at 40 and two at the lower speed, 30 will be equidistant, so 20 will be the answer but travelling has been more at lower so >20..a and B are out
only two C and D are left

_________________
Current Student
avatar
B
Status: Persevere
Joined: 09 Jan 2016
Posts: 118
Location: Hong Kong
GMAT 1: 750 Q50 V41
GPA: 3.52
Reviews Badge
Re: Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If  [#permalink]

Show Tags

New post 23 Feb 2016, 09:59
2
1
Bunuel wrote:
Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If he then continued to ride at a different constant rate for another three hours, and at the end of the three hours his average speed for the entire five hour ride was 30mph, what was his average speed over the three hour portion of his ride?

A. 14 mph
B. 20 mph
C. 70/3 mph
D. 80/3 mph
E. 34 mph

Kudos for correct solution.


Average speed for first two hours, S1 = 40 mph
Distance travelled in these two hours, D1 = 80 miles

Average speed for the entire 5 hour ride, S = 30 mph
Total Distance traveller in the entire 5 hour ride, D = 30 x 5 = 150 miles.

Hence, distance traveller in the latter 3 hour period, D2 = D - D1 = 150 - 80 = 70
Average speed for the latter 3 hour period S2 = D2/3 = 70/3
Hence, the correct answer is C
VP
VP
avatar
P
Joined: 07 Dec 2014
Posts: 1179
Re: Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If  [#permalink]

Show Tags

New post 23 Feb 2016, 11:17
1
let s=average speed over three hour portion of ride
total distance=80+3s miles
total time=5 hours
average speed for entire trip=(80+3s)/5=30 mph
s=70/3 mph
Manager
Manager
avatar
B
Joined: 07 May 2015
Posts: 175
Location: India
GMAT 1: 660 Q48 V31
GPA: 3
GMAT ToolKit User
Re: Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If  [#permalink]

Show Tags

New post 23 Feb 2016, 13:03
2
1
In 2 hrs at 40mph he covered 80m
In 3 hrs at Xmph he covered 3Xm
(80+3X)/5=30
3X= 70
X=70/3
Ans:C
CEO
CEO
User avatar
V
Joined: 12 Sep 2015
Posts: 3586
Location: Canada
Re: Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If  [#permalink]

Show Tags

New post 23 Feb 2016, 16:54
1
Related Resources
The following free videos cover the concepts/strategies that are useful for answering this question:

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
Image
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 10564
Re: Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If  [#permalink]

Show Tags

New post 13 Aug 2017, 13:50
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: Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If   [#permalink] 13 Aug 2017, 13:50
Display posts from previous: Sort by

Marco rode his dirt bike at 40 miles per hour (mph) for two hours. If

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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®.