Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
06 Sep 2004, 22:46
Kudos
Bookmarks
Hi Folks,
A large cube 10cm on a side is composed of smaller cubes 1 cm on a side. The large cube is printed red on its outside surfaces and then all the cubes are mixed in a drum. If one cube is selected randomly, which of the following is the approximate probability that the cube will have at least one red face?
A) 1:6
B) 1:5
C) 1:4
D) 1:3
E) 1:2
My flawed solution - 1000 small cubes contained in the big cube. Each side has 10*10 = 100 cubes. So 6 outer sides of the large cube have 600 small cubes. Since large cube is painted on outside surfaces - these 600 small cubes are painted red - while 1000-600 = 400 cubes are not painted.
P(atleast one side painted) = 1- P(no side painted) = 1 - 400/1000 = 3/5
Evidently not one of the ans choices - what am I missing?
Thanks
Stuti
A large cube 10cm on a side is composed of smaller cubes 1 cm on a side. The large cube is printed red on its outside surfaces and then all the cubes are mixed in a drum. If one cube is selected randomly, which of the following is the approximate probability that the cube will have at least one red face?
A) 1:6
B) 1:5
C) 1:4
D) 1:3
E) 1:2
My flawed solution - 1000 small cubes contained in the big cube. Each side has 10*10 = 100 cubes. So 6 outer sides of the large cube have 600 small cubes. Since large cube is painted on outside surfaces - these 600 small cubes are painted red - while 1000-600 = 400 cubes are not painted.
P(atleast one side painted) = 1- P(no side painted) = 1 - 400/1000 = 3/5
Evidently not one of the ans choices - what am I missing?
Thanks
Stuti
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
06 Sep 2004, 23:13
Kudos
Bookmarks
Total numbe rof small cubes = 1000
Total number of cubes with atleast 1 red side = 6 x 100 - 12 x 10 = 480
(6 sides have 100 small ubes each; Each of the 10 cubes in the 12 edges has been accounted for in two sides' count. So we have to subtact 120)
Pb = 480/1000 ~ 1/2
E?
Total number of cubes with atleast 1 red side = 6 x 100 - 12 x 10 = 480
(6 sides have 100 small ubes each; Each of the 10 cubes in the 12 edges has been accounted for in two sides' count. So we have to subtact 120)
Pb = 480/1000 ~ 1/2
E?
totally there are 1000 small cubes. Only the outer layer of the larger cube is painted red. Therefore the cube which is one layer inside the outer layer ( 8 x 8 x 8) is not painted red.
No. of cubes that can be formed from 8 x 8 x 8 = 512.
No. of cubes that are painted red = 1000 - 512 = 488.
P (red cube ) = 488/1000 = 1/2.
Thanks.
No. of cubes that can be formed from 8 x 8 x 8 = 512.
No. of cubes that are painted red = 1000 - 512 = 488.
P (red cube ) = 488/1000 = 1/2.
Thanks.
Yups. E is right.
