gmat prep question

BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

This topic has expert replies

Post new topic Post Reply

Previous Topic Next Topic

yvonne12: Master | Next Rank: 500 Posts; Posts: 144; Joined: Wed Feb 07, 2007 4:13 pm

gmat prep question

by yvonne12 » Sun Mar 04, 2007 12:10 pm

Adam and beth each drove from smallville to crown city by different routes. Adam drove an average speed of 40 mph and completed the trip in 30 minutes. beth route was 5miles longer, and it took her 20 minutes more than adam to complete the trip how many miles per hour was beth 's average speed on this trip?

answer 30

please explain

Quote

Source: Beat The GMAT — Problem Solving | Sun Mar 04, 2007 12:10 pm

jayhawk2001: Community Manager; Posts: 789; Joined: Sun Jan 28, 2007 3:51 pm; Location: Silicon valley, California; Thanked: 30 times; Followed by:1 members

by jayhawk2001 » Sun Mar 04, 2007 5:44 pm

Total distance covered by Adam = 40 mph * 30 / 60 min = 20 miles

Beth's distance = 20 + 5 = 25 miles
Beth covers this distance in 30 + 20 = 50 minutes

If 50 minutes => 25 miles, then 60 minutes = 25 / 50 * 60 = 30 mph

Hence Beth's average speed was 30 miles per hour

Quote

yvonne12: Master | Next Rank: 500 Posts; Posts: 144; Joined: Wed Feb 07, 2007 4:13 pm

by yvonne12 » Mon Mar 05, 2007 7:57 am

Thank you, but accoding to the distance formula its

rate * time = distance why do you divide by sixty minutes?

also,

total distance / total time = average speed, why did you divide total distance by 60 min and 50 min.

Im even more confused..could someone explain this to me. I dont want to catch this question on the real GMAT with different numbers and not know exactly how to attack this question...

Quote

ssiva: Junior | Next Rank: 30 Posts; Posts: 16; Joined: Tue Feb 13, 2007 9:46 am; Location: California; Thanked: 1 times

by ssiva » Mon Mar 05, 2007 10:23 am

rate * time = distance

In the problem the rate is givem in mph which is miles per hour and time is in minutes. They have to be brought to a common reference: either hours or minutes.

Quote

yvonne12: Master | Next Rank: 500 Posts; Posts: 144; Joined: Wed Feb 07, 2007 4:13 pm

by yvonne12 » Mon Mar 05, 2007 4:58 pm

thank you for clearing that up for me.

Quote

GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8083; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Mon Jun 25, 2018 11:15 am

yvonne12 wrote:Adam and beth each drove from smallville to crown city by different routes. Adam drove an average speed of 40 mph and completed the trip in 30 minutes. beth route was 5miles longer, and it took her 20 minutes more than adam to complete the trip how many miles per hour was beth 's average speed on this trip?

Since Adam drove 30 minutes, or 1/2 hour, at an average speed of 40 mph, he drove 1/2 x 40 = 20 miles. Since Beth's route was 5 miles longer, she drove 25 miles. She also drove 20 minutes longer than Adam, so she drove for 50 minutes, or 5/6 hour. Thus, her average speed was

25/(5/6) = 25 x 6/5 = 30 mph

Answer: 30

Scott Woodbury-Stewart
Founder and CEO
[email protected]