A coin with heads on one side and tails on the other has a 1/2 probabi

Question

A coin with heads on one side and tails on the other has a 1/2 probability of landing on heads. If the coin is flipped three times, what is the probability of flipping 2 tails and 1 head, in any order?

(A) 1/8
(B) 1/3
(C) 3/8
(D) 5/8
(E) 2/3

(A) 1/8
(B) 1/3
(C) 3/8
(D) 5/8
(E) 2/3

Diablo21 · Answer

No of ways to get 2 tails and 1 head (TTH)= 3 ways (TTH, THT, HTT)

Also Prob(T)=Prob(H)= 1/2
Hence, 
Prob(TTH in any order)= 1/2*1/2*1/2 + 1/2*1/2*1/2 +1/2*1/2*1/2
=3/8

Hence,C

Posted from my mobile device

AlexTheTrainer · Answer

1. Write one example of the desired outcome: T H H

2. Label each event w/ its relevant probability: 1/2 1/2 1/2

3. Multiply across: 1/2 x 1/2 x 1/2 = 1/8
NOTE: This 1/8 is the specific probability of T H H.

4. Determine number of ways desired outcome can occur: T H H, H H T, and H T H = 3 ways
NOTE: step 4 often involves some kind of permutation formula.

5. Multiply result of step 3 by result of step 4: 1/8 x 3 = 3/8

Posted from my mobile device

sabstas · Answer

all possible events would be =  2^{3}  = 8 total events 
(2 is the number of outcomes either Heads or Tails, and the 3 represents how many times the coin is flipped)

determine how many events we want = HHT, HTH, THH 
therefore probability of  \frac{3}{8}

IMO C

Nitisha03 · Answer

Probability of head or tail is 1/2. Hence, the probability of 3 flips, will be 1/8 (1/2*1/2*1/2).
We need head 2 times and tail 1 time, so combination will be 3C2*1C1 = 3
Ans: 1/8*3 =3/8

Sr1994 · Answer

The probability of getting heads or tails in a coin flip is 1/2

We are flipping the coin 3 times, so, P = (1/2)*(1/2)*(1/2) = 1/8

Now, it is mentioned in the question that there is no order. 1 order is TTH. Since we have 2 T, we have to divide 3! by 2! to address the repetition.
Total order = 3!/2! = 3

Therefore, answer = 1/8 * 3 = 3/8

Answer C

BrushMyQuant · Answer

Given that coin is flipped three times and we need to find what is the probability of flipping 2 tails and 1 head, in any order?

Coin is tossed 3 times => Total number of cases =  2^3  = 8

Out of these 8 cases there are three cases where we can get 2 Tail and 1 Head. HTT, THT, TTH

=>  Probability of flipping 2 tails and 1 head, in any order  =  \frac{3}{8}

So,  Answer will be C 
Hope it helps!

Watch the following video to learn How to Solve Probability with Coin Toss Problems

https://www.youtube.com/watch?v=LRURv38kZw8

summerbummer · Answer

Using Binomial, this is easy:

P(T) = 1/2
P(H)= 1/2

According to Binomial Theorem:

3C2 x (1/2)^2 x (1/2)^1

3C2 - Because we want 2 tails
1/2 - Probability for tails 
(1/2)^2 - ^2 because we want to find out for 2 tails
(1/2)^1 - ^1 because 3-2 = 1

Formula for binomial probability distribution:
(a +n) ^n = nC0 x (a^r) x (b^0) + nC1 x (a ^1) x (b ^(n-1))......

Binomial can only be used if there are two outcomes, such as coin questions. Super easy if you understand!

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

A coin with heads on one side and tails on the other has a 1/2 probabi

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

A coin with heads on one side and tails on the other has a 1/2 probabi

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards