Question

A coin is biased so that the head is 3 times as likely to occur as tail. This coin is tossed until a head or three tails occur. If X denotes the number of tosses of the coin, then the mean of X is

• A. $\frac{21}{16}$<
• B. $\frac{15}{16}$
• C. $\frac{81}{64}$
• D. $\frac{37}{16}$

Answer 1

Answer: (A)

$\frac{21}{16}$<

Answer 2

The correct option is(A): $\frac{21}{16}$