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

 It is currently 16 Oct 2019, 22:26 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

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.  If Machine X can produce 80 widgets in 4 hours, how long would it take

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

Hide Tags

Math Expert V
Joined: 02 Sep 2009
Posts: 58390
If Machine X can produce 80 widgets in 4 hours, how long would it take  [#permalink]

Show Tags

1 00:00

Difficulty:   5% (low)

Question Stats: 92% (00:58) correct 8% (01:23) wrong based on 127 sessions

HideShow timer Statistics

If Machine X can produce 80 widgets in 4 hours, how long would it take machine X and Y working together, to produce 500 widgets?

(1) Machine Y works at 3/4 the speed of machine X
(2) If Machine Y's speed doubled, it would produce 120 widgets in 4 hours

Kudos for correct solution.

_________________
Intern  Joined: 25 Jun 2014
Posts: 42
GMAT 1: 690 Q48 V37 WE: Operations (Computer Software)
Re: If Machine X can produce 80 widgets in 4 hours, how long would it take  [#permalink]

Show Tags

1
(1) Machine Y works at 3/4 the speed of machine X
(2) If Machine Y's speed doubled, it would produce 120 widgets in 4 hours

As, X can produce 80 widgets in 4 hours
So, X can produce 20 widgets in 1 hours

Statement 1: Sufficient.

Y works at 3/4 the speed of machine X
So, Y can produce 15 widgets in 1 hours (3/4 of 20)

X and Y together can produce 35 widgets in 1 hours.
X and Y together can produce 500 widgets in (500/35) = 14 Hours 17 mins

Statement 2: Sufficient.

Machine Y's speed doubled, it would produce 120 widgets in 4 hours
Machine Y's speed doubled, it would produce 30 widgets in 1 hours
Machine Y's at normal speed, it would produce 15 widgets in 1 hours

X and Y together can produce 35 widgets in 1 hours.
X and Y together can produce 500 widgets in (500/35) = 14 Hours 17 mins

_________________
Did I Help You..If Yes.. Then Kudos Please.. Senior Manager  Joined: 20 Aug 2015
Posts: 387
Location: India
GMAT 1: 760 Q50 V44 Re: If Machine X can produce 80 widgets in 4 hours, how long would it take  [#permalink]

Show Tags

Bunuel wrote:
If Machine X can produce 80 widgets in 4 hours, how long would it take machine X and Y working together, to produce 500 widgets?

(1) Machine Y works at 3/4 the speed of machine X
(2) If Machine Y's speed doubled, it would produce 120 widgets in 4 hours

Kudos for correct solution.

Given: Machine X can produce 80 widgets in 4 hours
Required: How long would it take machine X and Y working together, to produce 500 widgets

Statement 1: Machine Y works at 3/4 the speed of machine X
Rate of Machine X = 20 widgets per hour
Therefore rate of machine Y = 20*(3/4) = 15 widgets per hour.
Hence we can find out the time needed by machine X and Y together to produce 500 widgets
SUFFICIENT

Statement 2: If Machine Y's speed doubled, it would produce 120 widgets in 4 hours
Normal speed of machine Y = 60 widgets in 4 hours or 15 widgets/hour
Hence we can find out the time needed by machine X and Y together to produce 500 widgets
SUFFICIENT

Option D
Manager  B
Joined: 25 Sep 2015
Posts: 101
Location: United States
GMAT 1: 700 Q48 V37 GPA: 3.26
Re: If Machine X can produce 80 widgets in 4 hours, how long would it take  [#permalink]

Show Tags

Bunuel wrote:
If Machine X can produce 80 widgets in 4 hours, how long would it take machine X and Y working together, to produce 500 widgets?

(1) Machine Y works at 3/4 the speed of machine X
(2) If Machine Y's speed doubled, it would produce 120 widgets in 4 hours

Kudos for correct solution.

X rate - 20W/hr

A) Y rate 3*20/4=15W/hr
Rx+Ry=R(total).
500/Rtotal = total time working together. /
Sufficient

B) 120/4hr ----> 60/4hr----> 15W/hr. Same info as A.
Sufficient.

D.
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8011
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: If Machine X can produce 80 widgets in 4 hours, how long would it take  [#permalink]

Show Tags

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

If Machine X can produce 80 widgets in 4 hours, how long would it take machine X and Y working together, to produce 500 widgets?

(1) Machine Y works at 3/4 the speed of machine X
(2) If Machine Y's speed doubled, it would produce 120 widgets in 4 hours

In the original condition, it gives power of X and 500 widgets. So you need to figure out power of Y, which makes 1 variable. In order to match with the number of equations, you need 1 equation. However, for 1) 1 equation, for 2) 1 equation, which is likely to make D the answer.
For 1), power of Y=power of (3/4)X=(3/4)(80widgets/4hrs)=15widgets/1hr, which is unique and sufficient.
For 2), power of 2Y=120widgets/4hrs. Then, power of Y is 13widgets/1hr, which is unique and sufficient.
Therefore, the answer is D.

 For cases where we need 1 more equation, such as original conditions with “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.
_________________
Non-Human User Joined: 09 Sep 2013
Posts: 13204
Re: If Machine X can produce 80 widgets in 4 hours, how long would it take  [#permalink]

Show Tags

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________ Re: If Machine X can produce 80 widgets in 4 hours, how long would it take   [#permalink] 17 Oct 2018, 10:22
Display posts from previous: Sort by

If Machine X can produce 80 widgets in 4 hours, how long would it take

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

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