Question
The average of three numbers a, b and c is 2 more than
c. The average of a and b is 48. If d is 10 less than c, then the average of c and d is:Solution
Average of a and b = (a + b)/2 ⇒ (a + b)/2 = 48 ⇒ a + b = 96 ----(i) Average of three numbers a, b, and c = (a + b + c)/3 ⇒ (a + b + c)/3 = 12 + c ⇒ a + b + c = 36 + 3c ⇒ a + b = 36 + 2c Using (i), ⇒ 96 = 36 + 2c ⇒ 2c = 60 ⇒ c = 30 Then, ⇒ d = 30 – 10 ⇒ d = 20 Average of c and d = (c + d)/2 ⇒ (30 + 20)/2 ⇒ 50/2 ⇒ 25 ∴ The average of c and d is 25
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