A coin is flipped 12 times. What is the probability of getting exactly 8 heads?

2 Answers
Nov 3, 2016

Probability of getting exactly 8 heads in tossing a coin 12 times is #495/4096.#

Explanation:

If a coin is tossed 12 times, the maximum probability of getting heads is 12.
But, 12 coin tosses leads to #2^12#, i.e. 4096 number of possible sequences of heads & tails.

Let E be an event of getting heads in tossing the coin and S be the sample space of maximum possibilities of getting heads. Then probability of the event E can be defined as,

#P(E)=(n(E))/(n(S)).# [Where, n represents number accordingly].

#:.P(E)=495/4096.# (answer).

NOTE: To know more about probability, please check into :
http://www.careerbless.com/aptitude/qa/probability_imp.php.

Nov 3, 2016

#495/4096#

Explanation:

The number of possible sequences of heads and tails in #12# coin tosses is:

#2^12 = 4096#

The number of ways that such a sequence could contain exactly #8# heads is the number of ways of choosing #8# out of #12#...

#((12),(8)) = (12!)/((8!)(4!)) = (12xx11xx10xx9)/(4xx3xx2xx1) = 495#

So the probability of exactly #8# heads in #12# coin tosses is:

#495/4096#