Moderate -0.3 This is a straightforward probability question requiring students to list favorable outcomes for a sum of 9 (pairs: 3+6, 4+5, 5+4, 6+3), calculate each probability using given values, and sum them. It's slightly easier than average as it involves basic enumeration and multiplication of probabilities with no conceptual subtlety, though the biased die adds minor complexity over a standard fair die problem.
1 A biased die has faces numbered 1 to 6 . The probabilities of the die landing on 1,3 or 5 are each equal to 0.1 . The probabilities of the die landing on 2 or 4 are each equal to 0.2 . The die is thrown twice. Find the probability that the sum of the numbers it lands on is 9 .
1 A biased die has faces numbered 1 to 6 . The probabilities of the die landing on 1,3 or 5 are each equal to 0.1 . The probabilities of the die landing on 2 or 4 are each equal to 0.2 . The die is thrown twice. Find the probability that the sum of the numbers it lands on is 9 .\\
\hfill \mbox{\textit{CAIE S1 2017 Q1 [4]}}