Deb normally drives to work in 45 minutes at an average speed of 40 m/h. This week she plans to bike to work along a route that decreases the total distance she usually travels when driving by 20%. If Deb averages between 12 & 16 m/h when biking, how many minutes earlier will she need to leave in the morning in order to arrive at the same time as when she drives?
A 135
B 105
C 95
D 75
E 45
Speed/time
This topic has expert replies
-
- Master | Next Rank: 500 Posts
- Posts: 138
- Joined: Mon May 01, 2017 11:56 pm
- Thanked: 4 times
- GMATGuruNY
- GMAT Instructor
- Posts: 15539
- Joined: Tue May 25, 2010 12:04 pm
- Location: New York, NY
- Thanked: 13060 times
- Followed by:1906 members
- GMAT Score:790
Since Deb drives for 3/4 of an hour at a rate of 40 mph, the driving distance to work = rt = (40)(3/4) = 30 miles.vaibhav101 wrote:Deb normally drives to work in 45 minutes at an average speed of 40 m/h. This week she plans to bike to work along a route that decreases the total distance she usually travels when driving by 20%. If Deb averages between 12 & 16 m/h when biking, how many minutes earlier will she need to leave in the morning in order to arrive at the same time as when she drives?
A 135
B 105
C 95
D 75
E 45
Since the biking distance is 20% less than the driving distance, the biking distance = 30 - (1/5)(30) = 24 miles.
To guarantee an on-time arrival at even the least possible biking speed -- 12 mph -- the time required to travel 24 miles = d/r = 24/12 = 2 hours.
Since the time to work increases from 3/4 hour to 2 hours -- a difference of 1.25 hours -- Deb must leave 75 minutes early to guarantee an on-time arrival.
The correct answer is D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
GMAT/MBA Expert
- Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7222
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
Since 45 minutes = ¾ hour, the distance between her house and work is 40 x ¾ = 30 miles. This is her driving route. Since her biking route is 20% shorter, her biking route is 0.8 x 30 = 24 miles.vaibhav101 wrote:Deb normally drives to work in 45 minutes at an average speed of 40 m/h. This week she plans to bike to work along a route that decreases the total distance she usually travels when driving by 20%. If Deb averages between 12 & 16 m/h when biking, how many minutes earlier will she need to leave in the morning in order to arrive at the same time as when she drives?
A 135
B 105
C 95
D 75
E 45
To guarantee she will arrive at the same time as when she drives, we have to assume she bikes at her slow rate of 12 m/h. Thus it will take her 24/12 = 2 hours, or 120 minutes, to bike to work. So she has to leave 120 - 45 = 75 minutes earlier.
Answer: D
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews