Question

Suppose that a fair coin is tossed repeatedly and independently. Let X denote the number of tosses required to obtain for the first time a tail that is immediately preceded by a head. Then E(X) and P(X > 4), respectively, are

• A. 4 and $\frac{5}{16}$
• B. 4 and $\frac{11}{16}$
• C. 6 and $\frac{5}{16}$
• D. 6 and $\frac{11}{16}$

Answer 1

Answer: (A)

4 and $\frac{5}{16}$

Answer 2

The correct option is (A) : 4 and $\frac{5}{16}$.