Aptitude - Probability - Discussion
Discussion Forum : Probability - General Questions (Q.No. 5)
5.
Three unbiased coins are tossed. What is the probability of getting at most two heads?
Answer: Option
Explanation:
Here S = {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH}
Let E = event of getting at most two heads.
Then E = {TTT, TTH, THT, HTT, THH, HTH, HHT}.
 P(E) = |
n(E) | = | 7 | . |
| n(S) | 8 |
Discussion:
122 comments Page 7 of 13.
Venkat said:
1 decade ago
Answer is 3/8 i.e. (C).
H T H.
H H T.
T H H.
H T H.
H H T.
T H H.
Rajesh said:
1 decade ago
At most means 7/8.
At leat means 3/8.
At leat means 3/8.
Manu said:
1 decade ago
Thanks very helpful.
Kishore said:
1 decade ago
I think throwing 3 coins at a time is permutation not combination.
HTH = THH = HHT.
Reason is we did't mentioned the coins are different. So how can we say the first coin is Head second coin is Tail and third coin is Head.
If we throwing a single coin 3 times then we get combination like HHH, HHT, HTH, THH, TTT, THH, THT, TTH 8WAYS 1st throw second throw and third throw.
HTH = THH = HHT.
Reason is we did't mentioned the coins are different. So how can we say the first coin is Head second coin is Tail and third coin is Head.
If we throwing a single coin 3 times then we get combination like HHH, HHT, HTH, THH, TTT, THH, THT, TTH 8WAYS 1st throw second throw and third throw.
Kishore said:
1 decade ago
If the meaning of unbiased coin is different coins then the answer is correct.
Nandhini said:
1 decade ago
Guys I am confused about atleast and atmost. Can anyone give me a correct idea about that. I thought atleast 2 heads means we can have 2 heads and more than 2.
According to that we get 7/8. Then how do you get 7/8 for atmost 2 heads?
According to that we get 7/8. Then how do you get 7/8 for atmost 2 heads?
Mohan said:
1 decade ago
TTT there is no heads then why we consider that.
Trusha said:
1 decade ago
Hi guys I'm totally confused about 'or' and 'and' concept can anyone help please?
Rishal said:
1 decade ago
What is n(s)?
Pratyush said:
1 decade ago
At-most 2 means its 0, 1, or 2.
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