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?
3
4
1
4
3
8
7
8
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:
119 comments Page 1 of 12.

Sundar said:   1 decade ago
Hi Guys,

At most two heads means "Total number of HEADs can be 0 to 2".

So we cannot include HHH, because it contains 3 heads.

But we can include TTT, because ZERO head is accepted.

Therefore, the given answers is perfectively correct.

You may ask your doubts here if you have regarding this question?

Have a nice day!
(1)

Malarvizhi said:   1 decade ago
How did say n(s) is 8?

Sundar said:   1 decade ago
@Malarvizhi


Note: "At most two heads" --(means)--> Not more than two heads.

Here S = {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH} <--- (8 combinations)

Therefore, n(S) = 8.

Abhijit said:   1 decade ago
Total no of probabilities= 2^3 =8
for 2/1/0 heads probability is =7(only 1 left HHH)

Dharini said:   1 decade ago
I cant follow what abhijit said why it is 2 power 3?

Murugesh said:   1 decade ago
@dharini...
2---> H & T
3---> total no of coins.
so 2^3.

Dinesh said:   1 decade ago
Got it murugesh
thanks..

SATHYA said:   1 decade ago
What is unbiased coins?

Sathish said:   1 decade ago
Thank you sundar.

Sara said:   1 decade ago
Won't it be 3 out of 8?


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