Multiple choice

The average of a set of $10$ numbers is $15$. If one number is removed the average of the remaining numbers is $16$. What is the value of the number removed?

  1. $4$
  2. $5$
  3. $6$
  4. $7$
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C Correct answer
Explanation

Sum of 10 numbers = 10 * 15 = 150. Sum of 9 numbers = 9 * 16 = 144. Removed number = 150 - 144 = 6.

AI explanation

The total sum of the initial 10 numbers is calculated as 10 multiplied by 15, which equals 150. When one number is removed, the total sum of the remaining 9 numbers becomes 9 multiplied by 16, which equals 144. By subtracting the new sum from the old sum (150 minus 144), the value of the removed number is found to be 6.