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:
121 comments Page 5 of 13.
Kishore said:
10 years 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:
10 years ago
If the meaning of unbiased coin is different coins then the answer is correct.
Nandhini said:
10 years 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:
10 years ago
TTT there is no heads then why we consider that.
Trusha said:
10 years ago
Hi guys I'm totally confused about 'or' and 'and' concept can anyone help please?
Rishal said:
10 years ago
What is n(s)?
Pratyush said:
10 years ago
At-most 2 means its 0, 1, or 2.
Venkatesh said:
10 years ago
Why to consider the THT, TTH, HTT, TTT?
Namgay said:
10 years ago
We know there are 8 combinations but What is the trick to get the combinations when we toss three coins like HHH TTH?
Yadlapalli sivateja said:
10 years ago
To HHH condition:
H (1/2).
H (1/2)+3!/3! = 1/8.
H (1/2) answer = 1/8+3/8 = 1/2.
To TTH condition:
T(1/2).
T(1/2)+3!/2! = 3/8.
T (1/2).
H (1/2).
H (1/2)+3!/3! = 1/8.
H (1/2) answer = 1/8+3/8 = 1/2.
To TTH condition:
T(1/2).
T(1/2)+3!/2! = 3/8.
T (1/2).
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