Multiple choice

The mean of $4 $ terms is $28$ if one observation $12$ is mistaken as $21$ Find the right mean

  1. 24.75

  2. 25.75

  3. 24.25

  4. 25.25
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Original sum = 4 * 28 = 112. The error was replacing 12 with 21 (an increase of 9). Correct sum = 112 - 9 = 103. Correct mean = 103 / 4 = 25.75.

AI explanation

The original sum of the four terms is 4 times 28, which equals 112. Correcting the mistaken observation reduces the sum by subtracting the wrong value 21 and adding the right value 12, resulting in a new sum of 103. Dividing this new sum by the four terms gives a corrected mean of 25.75.

Keep practicing — related questions