Question

A coin is to be tossed until a head appears twice in a row. What is the sample space for this experiment? If the coin is fair, what is the probability that it will be tossed exactly four times?

Answer 1

Answer:
`(2)/(16)`

Explanation:

if the coin is tossed four times then the possible sample space is formed

`S=\left \{ HH, THH, HTHH, TTHH, HTTHH, THTHH, TTTHH, ...\right \}`

For the probability that the coin is tossed only four times is when

For tossing four times sample space is

S=( HHHH HHHT HHTH HHTT

HTHH HTHT HTTH HTTT

THHH THHT THTH THTT

TTHH TTHT TTTH TTTT )

out of the above required ones are HTHH,TTHH

so the probability is
`(2)/(16)`