Last visit was: 04 Oct 2024, 04:53 It is currently 04 Oct 2024, 04:53
Decision Tracker
My Rewards
Unanswered
Active Topics
New posts
New comers' posts
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

Working at their respective constant rates, machine A makes 100 copies

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 95937
Own Kudos [?]: 665025 [15]
Given Kudos: 87505
Send PM
CAT Tests Forum Quiz Mode
Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   24 Aug 2020, 21:44
14
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

95% (hard)

Question Stats:

40% (02:00) correct 60% (02:00) wrong based on 234 sessions
Hide Show DIFFICULTY AND TIMER STATISTICS
Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce?

(1) x = y.
(2) 5x + 4y = 90.


Are You Up For the Challenge: 700 Level Questions

 
ShowHide Answer
Official Answer
B
Most Helpful Reply
User avatar
L
yashikaaggarwal
Senior Moderator - Masters Forum
Joined: 19 Jan 2020
Posts: 3120
Own Kudos [?]: 2851 [9]
Given Kudos: 1510
Location: India
Schools: Cranfield (A) Warwick MiM "23 (M)
GPA: 4
WE:Analyst (Internet and New Media)
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   24 Aug 2020, 22:04
8
Kudos
1
Bookmarks
1 hour = 500 copies (Machine A)
2 hours = 1000 copies


1 hour = 400 copies (Machine B)
2 hours = 800 copies

Together they make 1800 copies per hour.

1) X=Y but what no. Of machines are working together?
1800, 3600, 5400 or more?
No idea.
(Insufficient)

2) 5x+4y = 90

X = 2 , Y = 20
Copies to be manufactured = 1000*2+20*800 = 2000+16000 = 18000

6 = X, Y = 15
Copies to be manufactured = 1000*6+15*800 = 6000+12000 = 18000

X = 10, Y = 10
Copies to be manufactured = 1000*10+10*800 = 10000+8000 = 18000

X = 14 , y = 5
Copies to be manufactured = 1000*14+5*800 = 14000+4000 = 18000

X = 18, Y = 0
Copies to be manufactured = 1000*18+0*800 = 18000

Manufactured copies no. Are same.
(Sufficient)

Answer is B

Posted from my mobile device
User avatar
B
Dan1sh
Joined: 22 Feb 2020
Posts: 8
Own Kudos [?]: 12 [5]
Given Kudos: 170
Location: India
GMAT 1: 640 Q47 V31
GPA: 4
WE:General Management (Manufacturing)
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   25 Aug 2020, 00:37
4
Kudos
1
Bookmarks
Machine A
12 mins --> 100 copies
2 hours --> 1000 copies

Machine B
15 mins --> 100 copies
2 hours --> 1000 copies

x no.of Machine A & y no.of Machine B

Total production in 2 hours = 1000x+800y=?

Statement I :
x=y cannot determine value of 1000x+800y
Not Sufficient

Statement II :
5x + 4y = 90

200* (5x + 4y = 90)

---> 1000x+800y=90*200

Sufficient


Option B

Posted from my mobile device
General Discussion
avatar
G
suchita2409
Joined: 11 May 2019
Posts: 166
Own Kudos [?]: 119 [1]
Given Kudos: 298
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   24 Aug 2020, 21:59
1
Bookmarks
It has to be C.

We need to find x and y to solve the problem.

First stmt is clearly insufficient.

Second stmt ,we can have no. of such pairs that could satisfy the equation.
Insufficient.

1)+2)
We get x=y=10

We can find out if we have values of x and y.

Posted from my mobile device
User avatar
B
ataman
Joined: 19 Oct 2015
Posts: 36
Own Kudos [?]: 10 [1]
Given Kudos: 49
Concentration: Finance, Strategy
GPA: 3.36
WE:Operations (Finance: Venture Capital)
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   24 Aug 2020, 23:02
1
Kudos
Very smart one! I had C then I aware yashikaaggarwal ‘s point. Tricky one

Posted from my mobile device
User avatar
L
yashikaaggarwal
Senior Moderator - Masters Forum
Joined: 19 Jan 2020
Posts: 3120
Own Kudos [?]: 2851 [0]
Given Kudos: 1510
Location: India
Schools: Cranfield (A) Warwick MiM "23 (M)
GPA: 4
WE:Analyst (Internet and New Media)
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   24 Aug 2020, 23:10
ataman
Very smart one! I had C then I aware yashikaaggarwal ‘s point. Tricky one

Posted from my mobile device
I was thinking about C initially as well. But I had been through similar DS question where C was the trap. So put it down on paper. And it turned out well. ?
User avatar
B
Ahmed9955
Joined: 18 Feb 2019
Posts: 85
Own Kudos [?]: 22 [0]
Given Kudos: 327
Location: India
Schools: Booth '24 Fuqua '24 ISB '23 NTU NUS Ross '24 Rotman '24 Yale '24
GMAT 1: 570 Q46 V21
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   03 Dec 2020, 00:57
Bunuel
Working at their respective constant rates, machine A makes 100 copies in 12 minutes and machine B makes 100 copies in 15 minutes. If a number of x machine A and a number of y machine B work simultaneously at their respective rates for 2 hours, what is the total number of copies that they will produce?

(1) x = y.
(2) 5x + 4y = 90.


Are You Up For the Challenge: 700 Level Questions


Project DS Butler Data Sufficiency (DS3)


For DS butler Questions Click Here

• MAIN POINT-Always check the equation you derive from questions with the equations given in statements.

Ra= rate of work of machine A => given - Ra =100/12
Rb = rate of work of Machine B => given - Ra =100/15

Time*Rate=Work done
To find- 2* (xRa + yRb ) =>2* (x*100/12 + y*100/15)=> 2*( x*25/3+y*20/3) -------(1)

S1 -> x=y

Clearly insufficient, we will still be left with one variable

S2-> 5x +4y=90
Now if I multiply the given eq with 5/3 I'll get

25/3x +20/3y=90
Put this value back in (1) - Sufficient

IMO -B
User avatar
B
drambo24
Joined: 09 Aug 2023
Posts: 6
Own Kudos [?]: 0 [0]
Given Kudos: 1
Location: India
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   08 Aug 2024, 08:43
hi bunuel could explain as to why option 2 is sufficient?shall we solve the equation from question stem and match with option 2?
User avatar
P
DmitryFarber
Manhattan Prep Instructor
Joined: 22 Mar 2011
Posts: 2746
Own Kudos [?]: 7947 [2]
Given Kudos: 56
GMAT 2: 780  Q50  V50
Send PM
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink] Working at their respective constant rates, machine A makes 100 copies   11 Aug 2024, 01:23
2
Kudos
Expert Reply
drambo24
hi bunuel could explain as to why option 2 is sufficient?shall we solve the equation from question stem and match with option 2?
­Yes, basically. Since the rates for A and B are 1,000/2 hrs and 800/2 hrs respectively, the total work we want is 1,000x + 800y. Statement 2 gives us the value for 5x + 4y. The trick is to recognize that the ratio of coefficients is the same. As shown in a previous explanation, if we multiply both sides of our equation by 200, we get the answer: 5x + 4y = 90 --> 1000x + 800y = 18,000

This issue of coefficient ratios is common in DS. In this case, it was the way to spot a sufficient statement. In many other cases, it appears as a trap. For instance, if the question had told us 5x+ 4y = 90 and then asked for x, then each statement might have shown another equation. If (1) had an equation with a different ratio of coefficients, such as 2x - y = -3, we could use that in conjunction with the previous equation to solve. But then if (2) gave us 1,000x + 800y = 18,000, it would be important for us to recognize that this was the same info we had from the question stem. In that case, we'd choose A, because (1) would be sufficient but (2) would not.
GMAT Club Bot
gmatclubot
Re: Working at their respective constant rates, machine A makes 100 copies [#permalink]
11 Aug 2024, 01:23
Moderator:
Bunuel
Math Expert
95937 posts