BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

A weighted coin has a probability p of showing heads. Is the

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Moderator
Posts: 7187
Joined: Thu Sep 07, 2017 4:43 pm
Followed by:23 members

A weighted coin has a probability p of showing heads. Is the

by BTGmoderatorDC » Tue Jun 18, 2019 11:19 pm

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

A weighted coin has a probability p of showing heads. Is the value of p > 0.2?


(1) Successive flips are independent, and the probability of getting at least one head in two flips is greater than 0.5.

(2) The probability of getting tail on a flip of coin is less than 0.8.

OA D

Source: Magoosh
Top
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 am
Location: Grand Central / New York
Thanked: 470 times
Followed by:34 members

by Jay@ManhattanReview » Wed Jun 19, 2019 6:31 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

BTGmoderatorDC wrote:A weighted coin has a probability p of showing heads. Is the value of p > 0.2?


(1) Successive flips are independent, and the probability of getting at least one head in two flips is greater than 0.5.

(2) The probability of getting tail on a flip of coin is less than 0.8.

OA D

Source: Magoosh
Say the probability of getting a head = p; thus, the probability of getting tail = 1 - p.

We have to determine whether p > 0.2.

Let's take each statement one by one.

(1) Successive flips are independent, and the probability of getting at least one head in two flips is greater than 0.5.

Scenario 1: Head and Tail; Probability = p*(1 - p)
Scenario 2: Both Heads; Probability = p^2

From Statement 1, we have p*(1 - p) + p^2 > 0.5 => p > 0.5. The answer is yes, p > 0.2 Sufficient.

(2) The probability of getting tail on a flip of the coin is less than 0.8.

=> (1 - p) < 0.8 => p > 0.2. Sufficient.

The correct answer: D

Hope this helps!

-Jay
_________________
Manhattan Review GMAT Prep

Locations: GRE Manhattan | ACT Prep Courses San Francisco | IELTS Prep Courses Boston | Seattle IELTS Tutoring | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Top
Post new topic Post Reply
• Page 1 of 1