GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

It is currently 12 Jul 2020, 12:16

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.

Close

Request Expert Reply

Confirm Cancel

If the probability that Brendon, Daniel and Kane score more than or eq

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 65194
If the probability that Brendon, Daniel and Kane score more than or eq  [#permalink]

Show Tags

New post 02 Jun 2020, 07:04
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

49% (02:20) correct 51% (02:20) wrong based on 39 sessions

HideShow timer Statistics

Kellogg School Moderator
avatar
B
Joined: 25 Aug 2015
Posts: 44
GMAT 1: 590 Q48 V21
GMAT 2: 620 Q49 V25
CAT Tests
Re: If the probability that Brendon, Daniel and Kane score more than or eq  [#permalink]

Show Tags

New post 02 Jun 2020, 07:51
Bunuel wrote:
If the probability that Brendon, Daniel and Kane score more than or equal to 700 on the GMAT is 0.4, 0.5 and 0.6 respectively, what is the probability that at least 2 of them score less than 700?

A. 0.12
B. 0.38
C. 0.40
D. 0.50
E. 0.60


probability that at least 2 of them score less than 700= probability that 2 of 3 score less than 700 + probability that all 3 score less than 700

probability that Brendon, Daniel and Kane score more than or equal to 700 on the GMAT is 0.4, 0.5 and 0.6 respectively
probability that Brendon, Daniel and Kane score less than 700 on the GMAT is (1-0.4), (1-0.5) and (1-0.6) respectively
probability that Brendon, Daniel and Kane score less than 700 on the GMAT is (0.6), (0.5) and (0.4) respectively


probability that 2 of 3 score less than 700 = probability that (B+D, D+K, K+B) score less than 700 or probability that (B,D, NOT K; D,K, NOT B; K,B, NOT D) score less than 700 = 0.6*0.5*0.6+ 0.5*0.4*0.4+ 0.4*0.6*0.5 = 0.180+ 0.080+ 0.120 = 0.380
probability that all 3 of them score less than 700= 0.6*0.5*0.4= 0.120

probability that at least 2 of them score less than 700= 0.380+0.120 = 0.500 or D
CEO
CEO
User avatar
V
Joined: 03 Jun 2019
Posts: 3235
Location: India
GMAT 1: 690 Q50 V34
WE: Engineering (Transportation)
Premium Member Reviews Badge CAT Tests
Re: If the probability that Brendon, Daniel and Kane score more than or eq  [#permalink]

Show Tags

New post 02 Jun 2020, 08:45
Bunuel wrote:
If the probability that Brendon, Daniel and Kane score more than or equal to 700 on the GMAT is 0.4, 0.5 and 0.6 respectively, what is the probability that at least 2 of them score less than 700?

A. 0.12
B. 0.38
C. 0.40
D. 0.50
E. 0.60


Asked: If the probability that Brendon, Daniel and Kane score more than or equal to 700 on the GMAT is 0.4, 0.5 and 0.6 respectively, what is the probability that at least 2 of them score less than 700?

The probability that at least 2 of them score less than 700 = The probability that at most 1 of them score more than or equal to 700 = (None scoring >=700) + (1 scoring >=700) = .6*.5*.4 + .6*.5*.6 + .4*.5*.6 + .4*.5*.4 = .120 + .180 + .120 + .080 = .5

IMO D
_________________
Kinshook Chaturvedi
Email: kinshook.chaturvedi@gmail.com
IESE School Moderator
avatar
S
Joined: 11 Feb 2019
Posts: 308
CAT Tests
Re: If the probability that Brendon, Daniel and Kane score more than or eq  [#permalink]

Show Tags

New post 03 Jun 2020, 13:26
IMO D
Brendon. scoring equal to or more than 700: b = 4/10, Brendon. scoring less than 700: not b = 6/10
Daniel scoring equal to or more than 700: k = 5/10, Daniel. scoring less than 700: not k = 5/10
Kane scoring equal to or more than 700: d = 6/10, Daniel. scoring less than 700: not d = 4/10

P(at least 2 of them score less than 700) = P(b * not k * not d) + P(not b * k * not d) + P(not b * not k * d) + P(not b * not k * not d)
= (4/10 * 5/10* 4/10) + (6/10 * 5/10 * 4/10) + (6/10 * 5/0* 6/10) + (6/10* 5/10* 4/10)
= 80/1000 + 120/1000 + 180/1000 + 120/1000 = 500/1000 = 1/2
_________________

Cheers,
NJ
Stanford School Moderator
avatar
B
Joined: 11 Jun 2019
Posts: 113
Location: India
Reviews Badge
Re: If the probability that Brendon, Daniel and Kane score more than or eq  [#permalink]

Show Tags

New post 05 Jun 2020, 09:28
Hey Bunuel, what is the correct method to solve this question?
Target Test Prep Representative
User avatar
V
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 11083
Location: United States (CA)
Re: If the probability that Brendon, Daniel and Kane score more than or eq  [#permalink]

Show Tags

New post 09 Jun 2020, 04:27
Bunuel wrote:
If the probability that Brendon, Daniel and Kane score more than or equal to 700 on the GMAT is 0.4, 0.5 and 0.6 respectively, what is the probability that at least 2 of them score less than 700?

A. 0.12
B. 0.38
C. 0.40
D. 0.50
E. 0.60


Solution:

We see that the probability that Brendon, Daniel, and Kane score less than 700 on the GMAT is 0.6, 0.5, and 0.4 respectively. The probability that at least 2 of them score less than 700 is the sum of the probability that exactly 2 of them score less than 700 and the probability that all 3 of them score less than 700. Therefore, we have:

There are 3 ways in which exactly 2 score less than 700. Letting Y = Yes and N = No, the 3 ways are (YYN), (YNY), and (NYY). We calculate the probability of each and add the three probabilities.

P(exactly 2 score less than 700) = 0.6 x 0.5 x 0.6 + 0.6 x 0.5 x 0.4 + 0.4 x 0.5 x 0.4 = 0.18 + 0.12 + 0.08 = 0.38

(Note: In the above calculation, the bolded factors are the probabilities that they score less than 700 and the unbolded factors are the probabilities that they score greater than or equal to 700.)

There is only 1 way in which all of them score less than 700: (YYY).

P(all 3 score less than 700) = 0.6 x 0.5 x 0.4 = 0.12

Therefore, P(at least 2 of them score less than 700) = 0.38 + 0.12 = 0.50.

Answer: D

_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

  214 REVIEWS

5-STARS RATED ONLINE GMAT QUANT SELF STUDY COURSE

NOW WITH GMAT VERBAL (BETA)

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

GMAT Club Bot
Re: If the probability that Brendon, Daniel and Kane score more than or eq   [#permalink] 09 Jun 2020, 04:27

If the probability that Brendon, Daniel and Kane score more than or eq

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





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