Question

A coin is tossed until a head appears or until it has been tossed three times . Given that head does not occur on the first toss, what is the probability that coin is tossed three times.

Answer 1

Answer:

the probability that the coin is tossed 3 times is 1/3

Answer 2

Answer:

The probability that coin tossed for three times is $\frac{2}{4}.$

Given:

A coin is tossed until a head appears or until it has been tossed three times.

Given that head does not occur on the first toss,  

To find:

The probability that coin is tossed three times

Solution:

The sample space = {HH, HT, TH, TT}

Since the head did not appear in the first toss, HH and HT is excluded.

The probability will be TT, TH.

Thus the probability will be $\frac{2}{4}.$

Result:

The probability that coin tossed for three times is $\frac{2}{4}.$