Multiple choice

The average of $x_1, x_2, x_3, x_4$ is 16. Half the sum of $x_2, x_3, x_4 $ is 23. What is the value of $x_1$?

  1. $17$
  2. $18$
  3. $19$
  4. $20$
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B Correct answer
Explanation

The sum of four numbers is 4 * 16 = 64. The sum of x2, x3, x4 is 2 * 23 = 46. Therefore, x1 = 64 - 46 = 18.

AI explanation

Using the formula for arithmetic mean, the sum of the four numbers is 16 times 4, which equals 64. The problem states that half the sum of the last three numbers is 23, meaning their full sum is 46. Subtracting 46 from the total sum of 64 gives the value of the first number as 18.