BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Machines X and Y run simultaneously at their respective cons

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 157
Joined: Sat Nov 19, 2016 5:34 am
Thanked: 2 times
Followed by:4 members

Machines X and Y run simultaneously at their respective cons

by hazelnut01 » Sun May 21, 2017 5:12 am
Machines X and Y run simultaneously at their respective constant rates. If machine X produces 400 bolts per hour, how many bolts do machines X and Y produce per hour?

(1) Machine X takes twice as long to produce 400 bolts as it does for machines X and Y, working together, to produce the same number of bolts.

(2) Machines X and Y produce bolts at the same rate.

OA=D
Top
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pm
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:511 members
GMAT Score:800

by [email protected] » Sun May 21, 2017 10:40 am
Hi ziyuenlau,

This DS question doesn't actually require that much 'math' - but you do have to keep track of the information that you're given to get the correct answer.

We're told that Machine X and Machine Y each have a constant rate of production (Machine X's rate is 400 bolts/hour) and that the Machines run simultaneously. We're asked how many bolts are produced by the 2 machines per hour.

1) Machine X takes twice as long to produce 400 bolts as it does for machines X and Y, working together, to produce the same number of bolts.

We already know that Machine X produces 400 bolts in 1 hour. Fact 1 tells us that 1 hour is TWICE as long as the time it takes the two machines to produce those same 400 bolts. Thus, the two machines (working together) can produce 400 bolts in 1/2 hour. We know that Machine X would produce 200 of those bolts in 1/2 hour, so the other 200 bolts must be produced by Machine Y during that time. We now know Machine Y's rate (it's 400 bolts/hour).
Fact 1 is SUFFICIENT.

2) Machines X and Y produce bolts at the same rate.

Since we already know that Machine X produces 400 bolts/hour, we now know that Machine Y also produces 400 bolts/hour.
Fact 2 is SUFFICIENT.

Final Answer: D

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
User avatar
Legendary Member
Posts: 2663
Joined: Wed Jan 14, 2015 8:25 am
Location: Boston, MA
Thanked: 1153 times
Followed by:128 members
GMAT Score:770

by DavidG@VeritasPrep » Sun May 21, 2017 1:02 pm
hazelnut01 wrote:Machines X and Y run simultaneously at their respective constant rates. If machine X produces 400 bolts per hour, how many bolts do machines X and Y produce per hour?

(1) Machine X takes twice as long to produce 400 bolts as it does for machines X and Y, working together, to produce the same number of bolts.

(2) Machines X and Y produce bolts at the same rate.

OA=D
1) If it takes X twice as long to produce 400 bolts as it does for the machines working together, and machine X can do 400 bolts in an hour, then we know that together they can do 400 bolts in 1/2 hour, or 800 bolts in one hour. Sufficient.

2) If X produces 400 bolts in an hour and Y produces 400 bolts in an hour, then clearly, they're doing 800 bolts in an hour together. Sufficient.

The answer is D.
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top
Post new topic Post Reply
• Page 1 of 1