WAEC Mathematics 2014 Theory — Question 19
Question 19 of 23 from the West African Examinations Council (WAEC) Mathematics 2014 Theory paper, with the correct answer and a full explanation.
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11. The table shows the distribution of outcomes when a die is thrown 50 times (Scores 1–6; Frequencies 2,5,13,11,9,10). Calculate the: (a) mean deviation of the distribution; (b) probability that a score selected at random is at least 4.
Model answer
Mean = Σfx/Σf = (1×2+2×5+3×13+4×11+5×9+6×10)/50 = (2+10+39+44+45+60)/50 = 200/50 = 4 (a) Mean deviation = Σf|x−mean|/Σf = [2(3)+5(2)+13(1)+11(0)+9(1)+10(2)]/50 = [6+10+13+0+9+20]/50 = 58/50 = 1.16 (b) P(score≥4) = (11+9+10)/50 = 30/50 = 3/5 = 0.6
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