Multiple choice

The average of a group of 18 numbers is 37.5. If 6 numbers of average x are added to them, then the average of all the numbers increases by 1. Then find the value of x is?

  1. 41.5

  2. 40

  3. 42

  4. 38.5

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A Correct answer
Explanation

Sum of 18 numbers = 18 × 37.5 = 675. Sum of 6 new numbers = 6x. New sum = 675 + 6x. New average = (675 + 6x)/24 = 38.5. Solving: 675 + 6x = 924, which gives 6x = 249, so x = 41.5. This is a straightforward average problem where the new average is given as 38.5 (37.5 + 1).