Multiple choice

The average of seven consecutive numbers is 21. If previous two numbers are also included, what will be the new average?

  1. 19

  2. 20

  3. 19.5

  4. 20.5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let the seven consecutive numbers be x-3, x-2, x-1, x, x+1, x+2, x+3. Their average is x = 21. If the previous two numbers (x-5 and x-4) are added, the new sum is (21*7) + (16 + 17) = 147 + 33 = 180. The new average is 180 / 9 = 20.

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