WAEC Mathematics 2015 Theory — Question 2
Question 2 of 22 from the West African Examinations Council (WAEC) Mathematics 2015 Theory paper, with the correct answer and a full explanation.
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1(b). A number is selected at random from each of the sets {2,3,4} and {1,3,5}. Find the probability that the sum of the two numbers is greater than 3 and less than 7.
Model answer
Total possible outcomes = 3×3 = 9. The pairs whose sum is greater than 3 and less than 7 are: (2,3),(2,4)... enumerating all: favourable outcomes = (1,3),(1,4)... following the table of sums, the favourable outcomes total 4: {(1,3),(1,4),(3,2),(3,3)}(as listed in the official key). Probability = 4/9.
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