Last visit was: 23 Apr 2026, 07:22 It is currently 23 Apr 2026, 07:22
Home
Messages
Tests
Schools
Events
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
Back to Forum
Create Topic
User avatar
guddo
User avatar
Joined: 25 May 2021
Last visit: 22 Apr 2026
Posts: 1,013
Own Kudos:
11,323
 [101]
Given Kudos: 32
Posts: 1,013
Kudos: 11,323
 [101]
The number of hours required for a certain company to produce 01 Dec 2023, 09:32
3
Kudos
Add Kudos
98
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

45% (medium)

Question Stats:

77% (02:22) correct 23% (02:44) wrong based on 887 sessions

History

Date
Time
Result
Not Attempted Yet

The number of hours required for a certain company to produce 1 unit of products X, Y, and Z, respectively, are shown in the table. Products X and Y can be produced simultaneously, and so can products X and Z; but products Y and Z cannot be produced simultaneously. What is the least number of hours required to produce a total of 10 units of product X, 5 units of product Y, and 7 units of product Z?

A. 35
B. 45
C. 55
D. 65
E. 85

Show Spoiler
Attachment:
2023-12-01_19-54-12.png
2023-12-01_19-54-12.png [ 11.2 KiB | Viewed 23116 times ]

Attachment:
2023-12-01_19-55-24.png
2023-12-01_19-55-24.png [ 74.91 KiB | Viewed 16480 times ]
ShowHide Answer
Official Answer
C
Trying to understand why the right answer is right? GMAT Club Tests explanations walk through concepts, shortcuts, and common traps on many questions. See how →
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,778
Own Kudos:
810,784
 [22]
Given Kudos: 105,853
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,778
Kudos: 810,784
 [22]
The number of hours required for a certain company to produce 01 Dec 2023, 09:38
9
Kudos
Add Kudos
13
Bookmarks
Bookmark this Post
guddo

The number of hours required for a certain company to produce 1 unit of products X, Y, and Z, respectively, are shown in the table. Products X and Y can be produced simultaneously, and so can products X and Z; but products Y and Z cannot be produced simultaneously. What is the least number of hours required to produce a total of 10 units of product X, 5 units of product Y, and 7 units of product Z?

A. 35
B. 45
C. 55
D. 65
E. 85

Show Spoiler
Attachment:
2023-12-01_19-54-12.png

Attachment:
2023-12-01_19-55-24.png
Show more

Since Y and Z cannot be produced simultaneously, let's calculate the amount of time required to produce 5 items of Y and 7 items of Z:

  • 5 items of Y would require 5*4 = 20 hours.
  • 7 items of Z would require 7*5 = 35 hours.

Since these products cannot be produced simultaneously, producing 5 items of Y and 7 items of Z together would require 20 + 35 = 55 hours.

Now, since producing 10 items of X requires 10*3 = 30 hours, and since item X can be paired either with products Y or Z, we can produce products X during those 55 hours without requiring additional time.

Therefore, only 55 hours are required to produce the required number of items.

Answer: C.
User avatar
KarishmaB
User avatar
Joined: 16 Oct 2010
Last visit: 23 Apr 2026
Posts: 16,441
Own Kudos:
79,393
 [7]
Given Kudos: 484
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,441
Kudos: 79,393
 [7]
The number of hours required for a certain company to produce 04 Jul 2024, 05:56
5
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
guddo

The number of hours required for a certain company to produce 1 unit of products X, Y, and Z, respectively, are shown in the table. Products X and Y can be produced simultaneously, and so can products X and Z; but products Y and Z cannot be produced simultaneously. What is the least number of hours required to produce a total of 10 units of product X, 5 units of product Y, and 7 units of product Z?

A. 35
B. 45
C. 55
D. 65
E. 85

Show Spoiler
Attachment:
2023-12-01_19-54-12.png

Attachment:
2023-12-01_19-55-24.png
Show more
­Note that Y and Z will be produced sequentially, no way around it. Which means that they will take 4*5 + 5*7 = 55 hours
Now 10 units of X will simply take 30 hrs and these can be clubbed with any 30 of the 55 hours. We do not need extra time for them.

Answer (C)
General Discussion
User avatar
gmatophobia
User avatar
Quant Chat Moderator
Joined: 22 Dec 2016
Last visit: 19 Apr 2026
Posts: 3,173
Own Kudos:
11,454
 [2]
Given Kudos: 1,862
Location: India
Concentration: Strategy, Leadership
Posts: 3,173
Kudos: 11,454
 [2]
The number of hours required for a certain company to produce 01 Dec 2023, 23:07
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
guddo

The number of hours required for a certain company to produce 1 unit of products X, Y, and Z, respectively, are shown in the table. Products X and Y can be produced simultaneously, and so can products X and Z; but products Y and Z cannot be produced simultaneously. What is the least number of hours required to produce a total of 10 units of product X, 5 units of product Y, and 7 units of product Z?

A. 35
B. 45
C. 55
D. 65
E. 85
Show more

As we require the least number of hours, we need to ensure that the products are produced as simultaneously as possible.

We can divide the production into two groups -

  • Group 1: X & Y ⇒ X & Y produces simultaneously
  • Group 2: X & Z ⇒ X & Z produces simultaneously

For Group 1, in 12 hours, 4 units of X are produced and 3 units of Y are produced.
For Group 2, in 15 hours, 5 units of X are produced and 3 units of Z are produced.

Attachment:
Screenshot 2023-12-02 111515.png
Screenshot 2023-12-02 111515.png [ 37.38 KiB | Viewed 19592 times ]

Assume that the production of X and Y is simultaneous, hence, in 12 hours we will have 4 units of X and 3 units of Y. After 24 hours, we will have 8 units of X and 6 units of Y. We need only 5 units of Y, the production of X and Y can run simultaneously for 24 - 4 = 20 hours.

In 20 hours we have produced 6 units of X and 5 units of Y.

We still need 4 units of X and 7 units of Z. Now the production of X and Z can start. As fewer units of X is required and the production of X is faster than the production of Z, the time required will depend on the time to produce 7 units of Z.

Time required to produce 7 units of Z = 7 * 5 = 35 hours

Total time required = 35 + 20 = 55 hours

Hence, we can eliminate D and E as they are greater than 55. Option A cannot be true as well, as 7 * 5 = 35. This is possible when the production of X, Y, and Z occurs simultaneously.

Option B, 45, is not possible as well, because the production of 7 units of Z alone takes 35 hours. Hence, if we produce X and Z together and let the production run for 35 hours. We will still need at least 5 * 4 = 20 hours to produce Y alone. Hence, 55 is the least possible hours.

Option C
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,960
Own Kudos:
1,117
 [1]
Posts: 38,960
Kudos: 1,117
 [1]
The number of hours required for a certain company to produce 23 Jul 2025, 03:43
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109778 posts
Krunaal
Tuck School Moderator
853 posts