Moderate -0.8 This is a straightforward expected value calculation requiring: (1) finding P(sum ≥ 7) by listing outcomes on two tetrahedral dice (routine enumeration of 16 equally likely outcomes), (2) multiplying by 200. It's simpler than average A-level questions as it involves only basic probability counting and one multiplication, with no complex probability concepts or multi-step reasoning.
2 Two unbiased tetrahedral dice each have four faces numbered \(1,2,3\) and 4. The two dice are thrown together and the sum of the numbers on the faces on which they land is noted. Find the expected number of occasions on which this sum is 7 or more when the dice are thrown together 200 times.
2 Two unbiased tetrahedral dice each have four faces numbered $1,2,3$ and 4. The two dice are thrown together and the sum of the numbers on the faces on which they land is noted. Find the expected number of occasions on which this sum is 7 or more when the dice are thrown together 200 times.
\hfill \mbox{\textit{CAIE S1 2009 Q2 [4]}}