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

It is currently 22 Oct 2019, 08:06

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

A does half as much work as B in three-fourth of the time. If together

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58428
A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 30 Jan 2019, 02:59
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

69% (02:41) correct 31% (02:58) wrong based on 108 sessions

HideShow timer Statistics

GMAT Club Legend
GMAT Club Legend
User avatar
D
Joined: 18 Aug 2017
Posts: 5031
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
GMAT ToolKit User Premium Member
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 30 Jan 2019, 03:33
1
Bunuel wrote:
A does half as much work as B in three-fourth of the time. If together they take 18 days to complete the work, how much time shall B take to do it

A. 40 days
B. 35 days
C. 30 days
D. 25 days
E. 20 days



for A given
work
x/2 = 3/4 * ra
ra = 2x/3
rb= x

given together a & b can do work in 18 days
or say
2x/3 + x= 1/18
5x=1/6
x= 1/30
days of b = 30 days
IMO C
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8125
Location: United States (CA)
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 01 Feb 2019, 19:12
Bunuel wrote:
A does half as much work as B in three-fourth of the time. If together they take 18 days to complete the work, how much time shall B take to do it

A. 40 days
B. 35 days
C. 30 days
D. 25 days
E. 20 days



We can let n = the number of days it takes B to complete the work by himself. Thus, B’s rate = 1/n and A’s rate = (1/2)/(3n/4) = 4/(6n) = 2/(3n). The sum of their individual rates is 1/18, and we create the equation:

2/(3n) + 1/n = 1/18

Multiplying by 18n, we have:

12 + 18 = n

30 = n

So it takes B 30 days to complete the job by himself.

Answer: C
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

VP
VP
avatar
P
Joined: 07 Dec 2014
Posts: 1224
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 01 Feb 2019, 21:09
Bunuel wrote:
A does half as much work as B in three-fourth of the time. If together they take 18 days to complete the work, how much time shall B take to do it

A. 40 days
B. 35 days
C. 30 days
D. 25 days
E. 20 days


B's time to complete work alone=t
A's rate=(1/2)/(3t/4)=2/3t
18(2/3t+1/t)=1
t=30 days
C
Intern
Intern
avatar
Joined: 19 May 2019
Posts: 3
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 22 May 2019, 15:39
How rate is calculated

Posted from my mobile device
Senior Manager
Senior Manager
User avatar
P
Joined: 03 Mar 2017
Posts: 366
Reviews Badge CAT Tests
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 27 May 2019, 19:34
1
Abedyeasin111 wrote:
How rate is calculated

Posted from my mobile device



The work done by A is 1/2 of B. Apply formula W=R*T. Therefore R=W/T.

W=1/2 Work(B) and T=3/4 of Time(B)

R(A)=(1/2(WB))/(3/4)(TB)

R(A)=2/3(RB) because WB/TB= RB by same W=R*T formula.

2/3B+1/B=1/18-----Final equation

Solve and you will get B=30

Hope this helps.
_________________
--------------------------------------------------------------------------------------------------------------------------
All the Gods, All the Heavens, and All the Hells lie within you.
VP
VP
avatar
P
Joined: 07 Dec 2014
Posts: 1224
A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 28 May 2019, 19:48
Bunuel wrote:
A does half as much work as B in three-fourth of the time. If together they take 18 days to complete the work, how much time shall B take to do it

A. 40 days
B. 35 days
C. 30 days
D. 25 days
E. 20 days


let B do 12 units of work per hour
and A do 12/2+6/3=8 units per hour
so B/A rate ratio=12/8=3/2
hence, B completes 3/5 of the house alone in the 18 hours working with A
and completes the remaining 2/5 in 12 hours working alone
18+12=30
C
Intern
Intern
avatar
B
Joined: 14 May 2019
Posts: 5
A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 29 May 2019, 13:55
Given:
A + B = 1/18

Also Given:
A => B/2 * 3/4T
B => B * T

We want to get A in terms of T. Multiply (B/2)*(4/3) and (3/4T)*(4/3)

Now:
A => B(2/3) * T
B => B * T

Plug this into our first equation:
B + B(2/3) = 1/18
B = 1/30
B = 30 Days
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8125
Location: United States (CA)
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 01 Jun 2019, 06:35
Bunuel wrote:
A does half as much work as B in three-fourth of the time. If together they take 18 days to complete the work, how much time shall B take to do it

A. 40 days
B. 35 days
C. 30 days
D. 25 days
E. 20 days


If we let n = the total number of days for B to complete the work, the rate of B is 1/n.

The rate of A is (1/2)/(3n/4) = 4/(6n) = 2/(3n)

Since they take 18 days to complete the job:

18/n + (18)[2/(3n)] = 1

18/n + 12/n = 1

18 + 12 = n

30 = n

So it takes B 30 days to complete the job.

Answer: C
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Manager
Manager
avatar
S
Joined: 23 Apr 2018
Posts: 139
Reviews Badge CAT Tests
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 01 Jun 2019, 07:58
1
warrior1991 wrote:
Abedyeasin111 wrote:
How rate is calculated

Posted from my mobile device



The work done by A is 1/2 of B. Apply formula W=R*T. Therefore R=W/T.

W=1/2 Work(B) and T=3/4 of Time(B)

R(A)=(1/2(WB))/(3/4)(TB)

R(A)=2/3(RB) because WB/TB= RB by same W=R*T formula.

2/3B+1/B=1/18-----Final equation

Solve and you will get B=30

Hope this helps.



Can you show how to solve this ? I am somehow unable to solve.

2/3B + 1/B = 18
I am taking
3B as their LCM

2+3/3B = 18

5/3B = 18
which is giving me 5 = 54B, and that's weird..please tell me, what's my mistake ?
Intern
Intern
avatar
B
Joined: 01 Jun 2019
Posts: 1
Re: A does half as much work as B in three-fourth of the time. If together  [#permalink]

Show Tags

New post 01 Jun 2019, 10:51
Shrey9 wrote:
warrior1991 wrote:
Abedyeasin111 wrote:
How rate is calculated

Posted from my mobile device



The work done by A is 1/2 of B. Apply formula W=R*T. Therefore R=W/T.

W=1/2 Work(B) and T=3/4 of Time(B)

R(A)=(1/2(WB))/(3/4)(TB)

R(A)=2/3(RB) because WB/TB= RB by same W=R*T formula.

2/3B+1/B=1/18-----Final equation

Solve and you will get B=30

Hope this helps.



Can you show how to solve this ? I am somehow unable to solve.

2/3B + 1/B = 18
I am taking
3B as their LCM

2+3/3B = 18

5/3B = 18
which is giving me 5 = 54B, and that's weird..please tell me, what's my mistake ?


You have to do the equation in terms of rate, so you set the equation to 1/18 (i.e. the rate), not 18 (the days).
GMAT Club Bot
Re: A does half as much work as B in three-fourth of the time. If together   [#permalink] 01 Jun 2019, 10:51
Display posts from previous: Sort by

A does half as much work as B in three-fourth of the time. If together

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





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne