A green and a yellow dice are rolled in order, then the probability that a sum greater than 9 is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( \displaystyle\frac{1}{6} \)
Two dice rolled in order give 6 × 6 = 36 equally likely ordered pairs. A sum greater than 9 means a sum of 10, 11 or 12.
\( \displaystyle \text{Sum }10:\ (4,6),(5,5),(6,4)\ \to\ 3 \)
\( \displaystyle \text{Sum }11:\ (5,6),(6,5)\ \to\ 2 \)
\( \displaystyle \text{Sum }12:\ (6,6)\ \to\ 1 \)
\( \displaystyle P=\frac{3+2+1}{36} \)
\( \displaystyle =\frac{6}{36}=\frac{1}{6} \)