Question

Two dice are rolled. If each die has six faces which are numbered $2,3,5,7,11,13$, then the probability that sum of the numbers on the top faces being a prime number is

• A. $\frac{1}{6}$
• B. $\frac{5}{36}$
• C. $\frac{1}{18}$
• D. $\frac{1}{9}$
• E. $\frac{1}{12}$

Answer 1

Answer: (A)

$S=\{2,3,5,7,11,13\}$ Sum is a prime no.
Favourable easer are
$(2,3),(3,2),(2,5),(9,2),(2,11),(11,2)$
$\therefore P=\frac{6}{36}=\frac{1}{6}$
Favourable easer are
$(2,3),(3,2),(2,5),(9,2),(2,11),(11,2)$
$\therefore P=\frac{6}{36}=\frac{1}{6}$