GMAT Changed on April 16th - Read about the latest changes here

It is currently 24 Apr 2018, 01:32

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Jack and Jill both left their respective homes at 1 PM. Jack walked

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

Hide Tags

Expert Post
e-GMAT Representative
User avatar
S
Joined: 04 Jan 2015
Posts: 1018
Jack and Jill both left their respective homes at 1 PM. Jack walked [#permalink]

Show Tags

New post 30 Jul 2017, 12:45
Expert's post
5
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

39% (02:59) correct 61% (02:27) wrong based on 90 sessions

HideShow timer Statistics

Jack and Jill both left their respective homes at 1 PM. Jack walked till a school that was between 2.5 kilometers and 3 kilometers from his home, inclusive, and returned home between 1:55 PM and 2:05 PM. If Jill walked 5 kilometers more than Jack and returned to her home at 3 PM, which of the following statements must be true?

    I. The walking speed of Jill was greater than that of Jack
    II. Jack’s walking speed was close to 3 kilometers per hour
    III. Had Jack covered 0.5 more kilometers every 30 minutes, his walking speed would have been greater than Jill’s


A. I only
B. II only
C. III only
D. I, II and III
E. None of the above



Thanks,
Saquib
Quant Expert
e-GMAT

Register for our Free Session on Number Properties (held every 3rd week) to solve exciting 700+ Level Questions in a classroom environment under the real-time guidance of our Experts :)

Image
[Reveal] Spoiler: OA

_________________












| '4 out of Top 5' Instructors on gmatclub | 70 point improvement guarantee | www.e-gmat.com

Senior CR Moderator
User avatar
V
Status: Long way to go!
Joined: 10 Oct 2016
Posts: 1367
Location: Viet Nam
GMAT ToolKit User Premium Member
Re: Jack and Jill both left their respective homes at 1 PM. Jack walked [#permalink]

Show Tags

New post 31 Jul 2017, 01:06
EgmatQuantExpert wrote:
Jack and Jill both left their respective homes at 1 PM. Jack walked till a school that was between 2.5 kilometers and 3 kilometers from his home, inclusive, and returned home between 1:55 PM and 2:05 PM. If Jill walked 5 kilometers more than Jack and returned to her home at 3 PM, which of the following statements must be true?

    I. The walking speed of Jill was greater than that of Jack
    II. Jack’s walking speed was close to 3 kilometers per hour
    III. Had Jack covered 0.5 more kilometers every 30 minutes, his walking speed would have been greater than Jill’s
A. I only
B. II only
C. III only
D. I, II and III
E. None of the above


At 1:00PM, Jack walked to school that was between 2.5-3 km from his home, and then returned home between 1:55PM-2:05PM. Hence, Jack walked about 5-6km in between 55min and 1h 05min.

At 1:00PM, Jill walked 5km more than Jack and returned home at 3PM, he walked about 10-11km in 2 hours.

(I) The walking speed of Jill was greater than that of Jack
We could set a specific example to eliminate this one.

If Jack walked for 5km in 1 hour, Jill walked for 10km in 2 hours, then the walking speed of them are equal.
If Jack walked for 6km in 1 hour, Jill walked for 11km in 2 hours, then the walking speed of Jack is greater.

Hence this one is wrong.

II. Jack’s walking speed was close to 3 kilometers per hour
It's clear that this one is wrong.
Jack walked about 5-6km in between 55min and 1h 05min. Hence, his walking speed is between 4.6 and 6.5 km per hour, much greater than 3 km per hour.

III. Had Jack covered 0.5 more kilometers every 30 minutes, his walking speed would have been greater than Jill’s
This one is correct.

If Jack covered 0.5 more km every 30 min, Jack will cover 1 more km every 1 hour. Hence, he could walk about 6-7km in between 55min and 65min.

Jill walked about 10-11km in 2 hours, or walked about 5-5.5km in 1 hours.

It's clear that Jack's walking speed is greater than Jill's. In the worst case, Jack could walk 6 km in 65 min, so his walking speed is 5.54km/h, still greater than Jill's.

The answer is C.
_________________

Actual LSAT CR bank by Broall

How to solve quadratic equations - Factor quadratic equations
Factor table with sign: The useful tool to solve polynomial inequalities
Applying AM-GM inequality into finding extreme/absolute value

New Error Log with Timer

Senior Manager
Senior Manager
User avatar
G
Joined: 03 Apr 2013
Posts: 290
Location: India
Concentration: Marketing, Finance
Schools: Simon '20
GMAT 1: 740 Q50 V41
GPA: 3
GMAT ToolKit User
Re: Jack and Jill both left their respective homes at 1 PM. Jack walked [#permalink]

Show Tags

New post 12 Dec 2017, 06:15
EgmatQuantExpert wrote:
Jack and Jill both left their respective homes at 1 PM. Jack walked till a school that was between 2.5 kilometers and 3 kilometers from his home, inclusive, and returned home between 1:55 PM and 2:05 PM. If Jill walked 5 kilometers more than Jack and returned to her home at 3 PM, which of the following statements must be true?

    I. The walking speed of Jill was greater than that of Jack
    II. Jack’s walking speed was close to 3 kilometers per hour
    III. Had Jack covered 0.5 more kilometers every 30 minutes, his walking speed would have been greater than Jill’s


A. I only
B. II only
C. III only
D. I, II and III
E. None of the above



Thanks,
Saquib
Quant Expert
e-GMAT

Register for our Free Session on Number Properties (held every 3rd week) to solve exciting 700+ Level Questions in a classroom environment under the real-time guidance of our Experts :)

Image


Though it's not a hard problem as far as the concepts go, the calculations involved are ugly at best.
_________________

Spread some love..Like = +1 Kudos :)

Expert Post
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 5776
Re: Jack and Jill both left their respective homes at 1 PM. Jack walked [#permalink]

Show Tags

New post 12 Dec 2017, 07:07
EgmatQuantExpert wrote:
Jack and Jill both left their respective homes at 1 PM. Jack walked till a school that was between 2.5 kilometers and 3 kilometers from his home, inclusive, and returned home between 1:55 PM and 2:05 PM. If Jill walked 5 kilometers more than Jack and returned to her home at 3 PM, which of the following statements must be true?

    I. The walking speed of Jill was greater than that of Jack
    II. Jack’s walking speed was close to 3 kilometers per hour
    III. Had Jack covered 0.5 more kilometers every 30 minutes, his walking speed would have been greater than Jill’s


A. I only
B. II only
C. III only
D. I, II and III
E. None of the above





Yes the calculations are lengthy, especially so in statement III and not likely to be seen in actual but you can save some time by..
info:-
1) Mr Jack travels 5 to 6 km in 55 to 65 min
2) Jill travels 10-11 in 2 hr

statements..
    I. The walking speed of Jill was greater than that of Jack
    To confirm, take MAX of Jack
    so Jill speed 5.5km/h and jacks speed 6 km in 55min, so >6km/h
    NOT necessary

    II. Jack’s walking speed was close to 3 kilometers per hour
    Don't do any calculations. REQUIRED info in statement I, speed of Jack>6km/h
    Again NOT necessary

    III. Had Jack covered 0.5 more kilometers every 30 minutes, his walking speed would have been greater than Jill’s
    so Jack travels 6 to 7 km in 55-65 min
    Take least speed of Jack 6 km in 65 min..
    Don't divide 6 by 65, will take a lot of time..
    check how much would JIll travel in 65 minutes = 65*5.5=357.5 whereas jack travels 6*60 = 360

    YES

Multiplication just lessens down some tedious calculations

Only III true

C
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html


GMAT online Tutor

Re: Jack and Jill both left their respective homes at 1 PM. Jack walked   [#permalink] 12 Dec 2017, 07:07
Display posts from previous: Sort by

Jack and Jill both left their respective homes at 1 PM. Jack walked

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


cron

GMAT Club MBA Forum Home| About| Terms and Conditions| 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®.