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

 It is currently 17 Aug 2018, 02:57

### 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

# A fair coin is to be flipped four times. What is the probability that

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 47949
A fair coin is to be flipped four times. What is the probability that  [#permalink]

### Show Tags

29 Jan 2018, 05:42
1
00:00

Difficulty:

25% (medium)

Question Stats:

50% (00:31) correct 50% (00:21) wrong based on 67 sessions

### HideShow timer Statistics

A fair coin is to be flipped four times. What is the probability that the coin will land on the same side on all four flips?

(A) 1/32
(B) 1/16
(C) 1/8
(D) 1/4
(E) 1/2

_________________
BSchool Forum Moderator
Joined: 26 Feb 2016
Posts: 3038
Location: India
GPA: 3.12
A fair coin is to be flipped four times. What is the probability that  [#permalink]

### Show Tags

29 Jan 2018, 06:22
Bunuel wrote:
A fair coin is to be flipped four times. What is the probability that the coin will land on the same side on all four flips?

(A) 1/32
(B) 1/16
(C) 1/8
(D) 1/4
(E) 1/2

There are two possibilities in which the coin will land - Head or Tail
The probability of the coin landing on either side is $$\frac{1}{2}$$

We have been asked to find the probability that the coin will land on the same side all 4 times.

Probability is $$\frac{1}{2}*\frac{1}{2}*\frac{1}{2}*\frac{1}{2}$$ that the coin lands a head every time
Probability is $$\frac{1}{2}*\frac{1}{2}*\frac{1}{2}*\frac{1}{2}$$ that the coin lands a tail every time

Hence, total probability is $$2*\frac{1}{2}*\frac{1}{2}*\frac{1}{2}*\frac{1}{2} = \frac{1}{8}$$(Option C)
_________________

You've got what it takes, but it will take everything you've got

Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2727
Re: A fair coin is to be flipped four times. What is the probability that  [#permalink]

### Show Tags

30 Jan 2018, 11:17
1
Bunuel wrote:
A fair coin is to be flipped four times. What is the probability that the coin will land on the same side on all four flips?

(A) 1/32
(B) 1/16
(C) 1/8
(D) 1/4
(E) 1/2

We have two options: all heads or all tails.

The probability of all heads is (1/2)^4 = 1/16, and the probability of all tails is also 1/16, so the total probability is 1/16 + 1/16 = 2/16 = 1/8.

_________________

Jeffery Miller

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

e-GMAT Representative
Joined: 04 Jan 2015
Posts: 1897
A fair coin is to be flipped four times. What is the probability that  [#permalink]

### Show Tags

31 Jan 2018, 01:25
Bunuel wrote:
A fair coin is to be flipped four times. What is the probability that the coin will land on the same side on all four flips?

(A) 1/32
(B) 1/16
(C) 1/8
(D) 1/4
(E) 1/2

Solution

• We are given that a fair coin is flipped four times.

o Each time, we will get either a head or a tail.
o Thus, total possible cases $$= 2 * 2 * 2 * 2 = 16$$
• We need to find the probability that the coin will land on the same side on all four flips.

o This is possible only when all the four time, we get all HEADs (HHHH) or all TAILs (TTTT)

o Thus, total favorable cases $$= 1 + 1 = 2$$

• Thus, the probability $$= \frac{Favorable Cases}{Total Cases} = \frac{2}{16} = \frac{1}{8}$$

The correct answer is Option C.

Regards,
Saquib
Quant Expert
e-GMAT
_________________

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
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

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

A fair coin is to be flipped four times. What is the probability that &nbs [#permalink] 31 Jan 2018, 01:25
Display posts from previous: Sort by

# Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.