Multiple choice

Average of 9 numbers is 20. If a number 30 is also included, then what will be the average of these 10 numbers?

  1. 20.5

  2. 21

  3. 19.5

  4. 21.5
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B Correct answer
Explanation

The sum of the original 9 numbers is 9 * 20 = 180. Adding 30 makes the new sum 180 + 30 = 210. The new average is 210 / 10 = 21.

AI explanation

The total sum of the initial 9 numbers is 9 times 20, which equals 180. When the number 30 is included, the new sum becomes 180 plus 30, which is 210. The new average of the 10 numbers is 210 divided by 10, which results in 21.

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