Multiple choice

Out of four numbers, the average of first 3 numbers is thrice the fourth number. If average of all four numbers is 15, what is 11 times of fourth number?

  1. 110

  2. 55

  3. 66

  4. 121

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let fourth number = x. Average of first three = 3x, so sum of first three = 9x. Average of all four = 15, so total sum = 60. Therefore 9x+x=60, 10x=60, x=6. Then 11×6=66. Option C is correct.

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