GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 16 Dec 2018, 12:36

### 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

## Events & Promotions

###### Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### Free GMAT Prep Hour

December 16, 2018

December 16, 2018

03:00 PM EST

04:00 PM EST

Strategies and techniques for approaching featured GMAT topics
• ### FREE Quant Workshop by e-GMAT!

December 16, 2018

December 16, 2018

07:00 AM PST

09:00 AM PST

Get personalized insights on how to achieve your Target Quant Score.

# A certain experiment has three possible outcomes. The outcomes are mut

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 51229
A certain experiment has three possible outcomes. The outcomes are mut  [#permalink]

### Show Tags

26 Jun 2018, 20:09
00:00

Difficulty:

15% (low)

Question Stats:

81% (01:16) correct 19% (01:33) wrong based on 65 sessions

### HideShow timer Statistics

A certain experiment has three possible outcomes. The outcomes are mutually exclusive and have probabilities p, $$\frac{p}{2}$$, and $$\frac{p}{4}$$, respectively. What is the value of p?

A) $$\frac{1}{7}$$

B) $$\frac{2}{7}$$

C) $$\frac{3}{7}$$

D) $$\frac{4}{7}$$

E) $$\frac{5}{7}$$

_________________
Math Expert
Joined: 02 Aug 2009
Posts: 7108
Re: A certain experiment has three possible outcomes. The outcomes are mut  [#permalink]

### Show Tags

26 Jun 2018, 21:06
Bunuel wrote:
A certain experiment has three possible outcomes. The outcomes are mutually exclusive and have probabilities p, $$\frac{p}{2}$$, and $$\frac{p}{4}$$, respectively. What is the value of p?

A) $$\frac{1}{7}$$

B) $$\frac{2}{7}$$

C) $$\frac{3}{7}$$

D) $$\frac{4}{7}$$

E) $$\frac{5}{7}$$

Mutually exclusive - In probability , two mutually exclusive or disjoint events MEANS both cannot occur together. example : a single coin toss, which can result in either heads or tails, but not both.

So this means there is no interaction of the 3 events and also there are only these three outcomes possible..
So addition of their probabilities should equal 1..
So $$P+\frac{P}{2}+\frac{P}{4}=1.......\frac{7P}{4}=1.........P=\frac{4}{7}$$

D
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

GMAT online Tutor

e-GMAT Representative
Joined: 04 Jan 2015
Posts: 2323
Re: A certain experiment has three possible outcomes. The outcomes are mut  [#permalink]

### Show Tags

26 Jun 2018, 21:28

Solution

Given:
• A certain experiment has three possible outcomes
• The outcomes are mutually exclusive and have probabilities $$p$$, $$\frac{p}{2}$$, and $$\frac{p}{4}$$, respectively

To find:
• The value of p

Approach and Working:
As the outcomes are mutually exclusive, any two or all 3 of them cannot occur at the same time

Also, as there are only 3 outcomes, the sum of their probabilities should be equal to 1
• Therefore, we can write, $$p + \frac{p}{2} + \frac{p}{4} = 1$$
Or, $$\frac{7p}{4} = 1$$
Or, $$p = \frac{4}{7}$$

Hence, the correct answer is option D.

_________________

Number Properties | Algebra |Quant Workshop

Success Stories
Guillermo's Success Story | Carrie's Success Story

Ace GMAT quant
Articles and Question to reach Q51 | Question of the week

Number Properties – Even Odd | LCM GCD | Statistics-1 | Statistics-2 | Remainders-1 | Remainders-2
Word Problems – Percentage 1 | Percentage 2 | Time and Work 1 | Time and Work 2 | Time, Speed and Distance 1 | Time, Speed and Distance 2
Advanced Topics- Permutation and Combination 1 | Permutation and Combination 2 | Permutation and Combination 3 | Probability
Geometry- Triangles 1 | Triangles 2 | Triangles 3 | Common Mistakes in Geometry
Algebra- Wavy line | Inequalities

Practice Questions
Number Properties 1 | Number Properties 2 | Algebra 1 | Geometry | Prime Numbers | Absolute value equations | Sets

| '4 out of Top 5' Instructors on gmatclub | 70 point improvement guarantee | www.e-gmat.com

Intern
Joined: 17 May 2018
Posts: 43
Re: A certain experiment has three possible outcomes. The outcomes are mut  [#permalink]

### Show Tags

11 Jul 2018, 08:18
1
Another way is to think of ratios. We need a ratio of 4:2:1 for the outcomes to respectively have probabilities p, p/2 and p/4. So the probability p of having the first outcome is 4/(4+2+1) = 4/7.
_________________

¿Tienes que presentar el GMAT y no sabes por dónde empezar?
¡Visita GMAT para Principiantes y recibe el curso completo gratis!

Re: A certain experiment has three possible outcomes. The outcomes are mut &nbs [#permalink] 11 Jul 2018, 08:18
Display posts from previous: Sort by