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When tossed, a certain coin has equal probability of landing on either
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When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time? A. 1/8 B. 1/4 C. 1/3 D. 3/8 E. 1/2
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Originally posted by young_gun on 25 Dec 2007, 12:52.
Last edited by Bunuel on 28 Apr 2015, 04:07, edited 3 times in total.
Renamed the topic, edited the question and added the OA.




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Re: Some PS questions Need explanation
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17 Aug 2010, 07:24
udaymathapati wrote: When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time?
A. 1/8 B. 1/4 C. 1/3 D. 3/8 E. 1/2 Winning scenario is if we'll have either three tails (TTT) or three heads (HHH): 1/2*1/2*1/2+1/2*1/2*1/2=1/4. Answer: B.
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Re: When tossed, a certain coin has equal probability of landing on either
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25 Dec 2007, 13:06
There are 8 possibilities for outcomes when flipping a fair coin 3 times.
2*2*2=2^3=8
of these 8 possibilities there are 2 with the coin landing on the same side each time. HHH and TTT.
so the probability is 2/8 or 1/4.
HHH  works
HHT
HTH
HTT
THH
THT
TTH
TTT  works
the standard .5*.5*.5=1/8 but that's just the probability of getting one SPECIFIC side 3 times in a row (ie probability of 3 heads). Since they don't care if it's 3 heads or 3 tails you have to multiply 1/8 by 2 (so now it's the probability of 3 heads OR 3 tails)




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When tossed, a certain coin has equal probability of landing
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17 Aug 2010, 06:18
When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time?
A. 1/8 B. 1/4 C. 1/3 D. 3/8 E. 1/2



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Re: Some PS questions Need explanation
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13 Jan 2014, 07:01
Bunuel wrote: udaymathapati wrote: Need help in explanation of following problems. Need to know how quickly we can solve such problems to save time.
4. When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time? A. 1/8 B.1/4 C.1/3 D.3/8 E.1/2
OA E Winning scenario is if we'll have either three tails (TTT) or three heads (HHH): 1/2*1/2*1/2+1/2*1/2*1/2=1/4. Answer: B. Hi Bunuel, if the question was "how high is the probability that you get only tails?" would it be answer B becaus 1/2*1/2*1/2 = 1/8?



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Re: Some PS questions Need explanation
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13 Jan 2014, 07:22
unceldolan wrote: Bunuel wrote: udaymathapati wrote: Need help in explanation of following problems. Need to know how quickly we can solve such problems to save time.
4. When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time? A. 1/8 B.1/4 C.1/3 D.3/8 E.1/2
OA E Winning scenario is if we'll have either three tails (TTT) or three heads (HHH): 1/2*1/2*1/2+1/2*1/2*1/2=1/4. Answer: B. Hi Bunuel, if the question was "how high is the probability that you get only tails?" would it be answer B becaus 1/2*1/2*1/2 = 1/8? Yes, P(TTT) = 1/2^3 = 1/8.
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Re: When tossed, a certain coin has equal probability of landing on either
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27 Apr 2015, 20:49
young_gun wrote: eschn3am wrote: There are 8 possibilities for outcomes when flipping a fair coin 3 times.
2*2*2=2^3=8
of these 8 possibilities there are 2 with the coin landing on the same side each time. HHH and TTT.
so the probability is 2/8 or 1/4.
HHH  works HHT HTH HTT THH THT TTH TTT  works
the standard .5*.5*.5=1/8 but that's just the probability of getting one SPECIFIC side 3 times in a row (ie probability of 3 heads). Since they don't care if it's 3 heads or 3 tails you have to multiply 1/8 by 2 (so now it's the probability of 3 heads OR 3 tails) thanks, i get that...just am not sure why the binomial distrib doesn't work for this problem... Complements of the GMAT Club Bot, I will attempt to answer your questions 8 years later. Binomial distribution doesn't work here because you must take into account the probability of HHH or TTT. = 1/8 + 1/8 = 2/8 = 1/4 This means you will add the two probabilities. You're likely confusing this question with something along the lines of "If I flip a coin 3 times, what is the probability of getting all heads" = 1/8 .



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Re: When tossed, a certain coin has equal probability of landing on either
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27 Apr 2015, 22:49
HHH or TTT = (1/2 * 1/2 * 1/2) + (1/2 * 1/2 * 1/2) = 1/8 + 1/8 = 1/4



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When tossed, a certain coin has equal probability of landing
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20 May 2015, 16:40
Probability of landing on the same side every time: 1  (1/2 + 1/4) = 1/4



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When tossed, a certain coin has equal probability of landing
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09 Apr 2017, 13:23
young_gun wrote: When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time?
A. 1/8 B. 1/4 C. 1/3 D. 3/8 E. 1/2 1st throw: Probability of getting either side = 1 2nd throw: Probability of getting the first side = 1/2 3rd throw: Probability of getting the first side = 1/2 (1/2)*(1/2)=1/4



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Re: When tossed, a certain coin has equal probability of landing
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18 Apr 2017, 16:44
young_gun wrote: When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time?
A. 1/8 B. 1/4 C. 1/3 D. 3/8 E. 1/2 We need to determine the probability that a coin lands on the same side for all 3 tosses of the coin. This means that the 3toss outcome will be either HHH or TTT. P(TTT) = 1/2 x 1/2 x 1/2 = 1/8 P(HHH) = 1/2 x 1/2 x 1/2 = 1/8 Thus, the probability that the coin lands on the same side each time is 1/8 + 1/8 = 2/8 = 1/4. Answer: B
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Re: When tossed, a certain coin has equal probability of landing
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13 Dec 2017, 14:32
young_gun wrote: When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 3 times, what is the probability that it will land on the same side each time?
A. 1/8 B. 1/4 C. 1/3 D. 3/8 E. 1/2 P(3 matching tosses) = P(ANY result on 1st toss AND 2nd toss matches 1st toss AND 3rd toss matches 2nd toss) = P(ANY result on 1st toss) x P(2nd toss matches 1st toss ) x P(3rd toss matches 2nd toss) = 1 x 1/2 x 1/2 = 1/4 = B Cheers, Brent
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Re: When tossed, a certain coin has equal probability of landing
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28 Feb 2018, 12:12
eschn3am wrote: There are 8 possibilities for outcomes when flipping a fair coin 3 times.
2*2*2=2^3=8
of these 8 possibilities there are 2 with the coin landing on the same side each time. HHH and TTT.
so the probability is 2/8 or 1/4.
HHH  works HHT HTH HTT THH THT TTH TTT  works
the standard .5*.5*.5=1/8 but that's just the probability of getting one SPECIFIC side 3 times in a row (ie probability of 3 heads). Since they don't care if it's 3 heads or 3 tails you have to multiply 1/8 by 2 (so now it's the probability of 3 heads OR 3 tails) Great explanation!!! Thank you!



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Re: When tossed, a certain coin has equal probability of landing
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16 Mar 2019, 08:49
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Re: When tossed, a certain coin has equal probability of landing
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