Multiple choice

Average of A, B and C is 45. A : B = 1 : 2 and B - A = 30, then find A + C.

  1. 85

  2. 65

  3. 80

  4. 75

  5. 90
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

(A+B+C)/3 = 45 => A+B+C = 135. A:B = 1:2 => B = 2A. B-A = 30 => 2A-A = 30 => A = 30. Then B = 60. A+B+C = 30+60+C = 135 => C = 45. A+C = 30+45 = 75.

AI explanation

Using the ratio A:B of 1:2, we can set A as x and B as 2x. Substituting these into the second given condition, B minus A equals 30, gives 2x minus x equals 30, meaning A is 30 and B is 60. Since the average of A, B, and C is 45, their total sum must be 3 multiplied by 45, which is 135. Therefore, A plus C equals the total sum of 135 minus B, giving 135 minus 60, which results in 75.

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