Last visit was: 21 Nov 2024, 06:20 It is currently 21 Nov 2024, 06:20

Close

GRE Prep 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 GRE 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
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3224 [13]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Most Helpful Community Reply
Manager
Manager
Joined: 05 Aug 2020
Posts: 101
Own Kudos [?]: 244 [4]
Given Kudos: 14
Send PM
General Discussion
Manager
Manager
Joined: 05 Aug 2020
Posts: 101
Own Kudos [?]: 244 [1]
Given Kudos: 14
Send PM
Intern
Intern
Joined: 30 Aug 2021
Posts: 20
Own Kudos [?]: 6 [0]
Given Kudos: 6
Send PM
Re: Working at their respective constant rates, Machine A takes 2 days [#permalink]
grenico wrote:
Answer is A.

The time it takes Machine A to make \(w\) widgets is 6 days, so to make \(2w\) widgets it would take 12 days.

I used algebra to solve this one and it's a pain to do, but will write it out if someone needs help with explanation :)

Can you please explain this?
Retired Moderator
Joined: 16 Apr 2020
Status:Founder & Quant Trainer
Affiliations: Prepster Education
Posts: 1546
Own Kudos [?]: 3224 [3]
Given Kudos: 172
Location: India
WE:Education (Education)
Send PM
Re: Working at their respective constant rates, Machine A takes 2 days [#permalink]
2
1
Bookmarks
Shortcut:

Work done by A + Work done by B = Total Work done
i.e. \(W_A + W_B = W_T\) ........ (1)

We know, Work = (Rate)(Time)

Let, Time required by machine B to produce \(w\) widgets be \(t\)
Then, Time required by machine B to produce \(w\) widgets will be \((t+2)\)

\(R_A = \frac{1}{(t+2)}\)
\(R_B = \frac{1}{t}\)

Total work done is \(\frac{5}{4}\) in 3 days
Now, using equation (1);

\(\frac{3}{(t+2)} + \frac{3}{t} = \frac{5}{4}\)

\(12t + 12t + 24 = 5t^2 + 10t\)
\(5t^2 - 14t - 24 = 0\)

Solve for \(t = 4\)
i.e. Machine will take \(4 + 2 = 6\) hours to produce \(w\) widgets

Col. A: \(6 + 6 = 12\)
Col. B: \(10\)

Hence, option A
Intern
Intern
Joined: 16 Nov 2023
Posts: 4
Own Kudos [?]: 1 [0]
Given Kudos: 4
Send PM
Re: Working at their respective constant rates, Machine A takes 2 days [#permalink]
Hi there, is there a way to get to the solution faster ? I managed to get to the right solution by finding t = 4 but it took me like 4 minutes so no way I can afford that :)
Thank you in advance guys
Verbal Expert
Joined: 18 Apr 2015
Posts: 29999
Own Kudos [?]: 36330 [0]
Given Kudos: 25923
Send PM
Re: Working at their respective constant rates, Machine A takes 2 days [#permalink]
Expert Reply
The solution provided above by Karun would take roughly 40 seconds.

I do not think is a big deal
Prep Club for GRE Bot
Re: Working at their respective constant rates, Machine A takes 2 days [#permalink]
Moderators:
GRE Instructor
83 posts
GRE Forum Moderator
37 posts
Moderator
1111 posts
GRE Instructor
234 posts

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