GRE Prep 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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
John flips a quarter coin twice
[#permalink]
12 Jan 2021, 09:17
12 Jan 2021, 09:17
Expert Reply
00:00
Question Stats:
65% (00:27) correct
34% (00:30) wrong based on 38 sessions
Hide Show timer Statistics
John flips a quarter coin twice
A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.
Kudos for the right answer and explanation
Quantity A |
Quantity B |
The chances of John getting two tails |
The chances of John getting NO tails |
A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.
Kudos for the right answer and explanation
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: John flips a quarter coin twice
[#permalink]
12 Jan 2021, 10:31
12 Jan 2021, 10:31
1
Carcass wrote:
John flips a quarter coin twice
Quantity A |
Quantity B |
The chances of John getting two tails |
The chances of John getting NO tails |
The correct answer here is actually D, since we're not told that this is a "fair" coin (i.e., on any toss, the probability of heads = probability of tails = 0.5)
IF we assume that P(heads) = P(tails) = 0.5, then...
P(two tails) = P(tails on first toss AND tails on second toss)
= P(tails on first toss) x) P(tails on second toss)
= 0.5 x 0.5
= 0.25
P(no tails) = P(2 heads)
P(heads on first toss AND heads on second toss)
= P(heads on first toss) x) P(heads on second toss)
= 0.5 x 0.5
= 0.25
Answer: C
Moderator
Joined: 02 Jan 2020
Status:GRE Quant Tutor
Posts: 1115
Given Kudos: 9
Location: India
Concentration: General Management
Schools: XLRI Jamshedpur, India - Class of 2014
GMAT 1: 700 Q51 V31
GPA: 2.8
WE:Engineering (Computer Software)
John flips a quarter coin twice
[#permalink]
23 Oct 2022, 09:10
23 Oct 2022, 09:10
Given that John flips a quarter coin twice
Quantity A: The chances of John getting two tails
As we are flipping a coin twice so there are \(2^2\) = 4 cases
HH, HT, TH, TT
The chances of John getting two tails = \(\frac{1}{4}\)
(As there is only one case TT out of 4 in which John can get two Tails)
Quantity B: The chances of John getting NO tails
The chances of John getting NO Tails = Chance of getting 2 heads= \(\frac{1}{4}\)
(As there is only one case HH out of 4 in which John can get NO tails or 2 Heads)
Clearly, Quantity A = Quantity B = \(\frac{1}{4}\)
So, Answer will be C
Hope it helps!
Watch the following video to learn How to Solve Probability with Coin Toss Problems
Quantity A: The chances of John getting two tails
As we are flipping a coin twice so there are \(2^2\) = 4 cases
HH, HT, TH, TT
The chances of John getting two tails = \(\frac{1}{4}\)
(As there is only one case TT out of 4 in which John can get two Tails)
Quantity B: The chances of John getting NO tails
The chances of John getting NO Tails = Chance of getting 2 heads= \(\frac{1}{4}\)
(As there is only one case HH out of 4 in which John can get NO tails or 2 Heads)
Clearly, Quantity A = Quantity B = \(\frac{1}{4}\)
So, Answer will be C
Hope it helps!
Watch the following video to learn How to Solve Probability with Coin Toss Problems
