 It is currently 24 Mar 2019, 10:02 ### 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. # A number cube has six faces numbered 1 through 6. If the cub  Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4857
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 105

Kudos [?]: 1783 , given: 397

A number cube has six faces numbered 1 through 6. If the cub [#permalink]
Expert's post 00:00

Question Stats: 53% (00:54) correct 46% (01:27) wrong based on 13 sessions
A number cube has six faces numbered 1 through 6. If the cube is rolled twice, what is the probability that at least one of the rolls will result in a number greater than 4?

(A) $$\frac{2}{9}$$
(B) $$\frac{1}{3}$$
(C) $$\frac{4}{9}$$
(D) $$\frac{5}{9}$$
(E) $$\frac{2}{3}$$
[Reveal] Spoiler: OA

_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Director  Joined: 07 Jan 2018
Posts: 604
Followers: 7

Kudos [?]: 544 , given: 88

Re: A number cube has six faces numbered 1 through 6. If the cub [#permalink]
The probability of both roll being 4 or less than 4 is $$\frac{4}{6} * \frac{4}{6} = \frac{16}{36}$$
Therefore the probability of a roll being more than 4 is $$1 - \frac{16}{36} = \frac{20}{36} = \frac{10}{18} = \frac{5}{9}$$
_________________

This is my response to the question and may be incorrect. Feel free to rectify any mistakes

GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4857
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 105

Kudos [?]: 1783 , given: 397

Re: A number cube has six faces numbered 1 through 6. If the cub [#permalink]
Expert's post
Explanation

Because this problem is asking for an “at least” solution, use the 1 – x shortcut.

The probability that at least one roll results in a number greater than 4 is equal to 1 minus the probability that both of the rolls result in numbers 4 or lower. For one roll, there are 6 possible outcomes (1 through 6) and 4 ways in which the outcome can be 4 or lower, so the probability is $$\frac{4}{6}=\frac{2}{3}$$.

Thus, the probability that both rolls result in numbers 4 or lower is $$\frac{2}{3}\frac{2}{3}=\frac{4}{9}$$.

This is the result that you do not want; subtract this from 1 to get the probability that you do want. The probability that at least one of the rolls results in a number greater than 4 is $$1 - \frac{4}{9} =\frac{5}{9}$$.
_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test Re: A number cube has six faces numbered 1 through 6. If the cub   [#permalink] 09 Aug 2018, 14:32
Display posts from previous: Sort by

# A number cube has six faces numbered 1 through 6. If the cub  Question banks Downloads My Bookmarks Reviews Important topics Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.