A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an : Problem Solving (PS)

My Profile Logout

Test's Subscription Expires:

My Follow Feed Kudos My Error Log

Messages and Replies

Settings Mark All Read

See All

Applicant Notifications

Settings Mark All Read

See All

Global notifications

Settings Mark All Read

See All

A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an

Sort by Date

Sort by Kudos

Author

Message

TAGS:

Hide Tags

Find Similar Topics

Math Expert

Joined: 02 Sep 2009

Posts: 58320

A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an [#permalink]

Show Tags

11 Jul 2016, 12:32

00:00

Difficulty:

5% (low)

Question Stats:

84% (01:18) correct

16% (01:55) wrong

based on 124 sessions

HideShow timer Statistics

A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for another 40 minutes. What was its average speed?

A. 80.
B. 75.
C. 70.
D. 65.
E. 54.

Spoiler: OA

_________________

What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Signature Read More

Current Student

Joined: 03 Apr 2016

Posts: 84

Location: India

Concentration: Technology, General Management

Schools: Kelley '19 (WD), IIMB EPGP "21 (D), S.P.Jain Institute (A)

GMAT 1: 720 Q50 V37

WE: Analyst (Computer Software)

Re: A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an [#permalink]

Show Tags

11 Jul 2016, 14:11

A. ( 60 * 1/3 + 90 * 2/3 ) / 1

Sent from my SM-N910H using Tapatalk

Director

Joined: 20 Feb 2015

Posts: 767

Concentration: Strategy, General Management

Re: A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an [#permalink]

Show Tags

12 Jul 2016, 00:12

driving at 60 Km/h for 20 minutes ,distance covered = 60*1/3=20 km
driving at 90 km/h for 40 minutes ,distance covered = 90*2/3=60 km

average speed = total distance/total time = 80/1 = 80 km/h

Manager

Joined: 07 May 2015

Posts: 174

Location: India

Schools: Kellogg '20, Yale '20, HEC Dec"18, ISB '19

GMAT 1: 660 Q48 V31

GPA: 3

Re: A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an [#permalink]

Show Tags

13 Jul 2016, 07:37

60*20/60 + 90*40/60
=20+60
=80
And:A

Senior Manager

Joined: 15 Sep 2011

Posts: 310

Location: United States

WE: Corporate Finance (Manufacturing)

Re: A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an [#permalink]

Show Tags

18 Jul 2016, 16:12

Top Contributor

The ratio of times traveled is 1:2 and time varies inversely with speed (2:1), then the weight of 90Km/h must be twice than that of 60Km/h .
Therefore, Option A. 80

Joined: 07 Dec 2014

Posts: 1223

A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an [#permalink]

Show Tags

18 Jul 2016, 19:19

3 equal time segments @ 60,90,90 mph
(60+90+90)/3=80 mph average speed

Board of Directors

Status: QA & VA Forum Moderator

Joined: 11 Jun 2011

Posts: 4765

Location: India

GPA: 3.5

WE: Business Development (Commercial Banking)

Re: A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for an [#permalink]

Show Tags

26 Oct 2018, 07:53

Bunuel wrote:

A car was driving at 60 Km/h for 20 minutes, and then at 90Km/h for another 40 minutes. What was its average speed?

A. 80.
B. 75.
C. 70.
D. 65.
E. 54.

Total Distance travelled is \(60*\frac{20}{60} + 90*\frac{40}{60}=80\)
Total Time taken is 20 min + 40 min = 60 Min = 1 Hour

So, Average speed is 80 km/hr ; Answer must be (A) 80
_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Signature Read More