Multiple choice

The mean of seven observations is $18$. A new observation $16$ is added. The mean of eight observations is _____.

  1. $22$
  2. $17.75$
  3. $18$
  4. None of them

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sum of 7 observations = 7 * 18 = 126. New sum = 126 + 16 = 142. New mean = 142 / 8 = 17.75.

AI explanation

The sum of the original seven observations is 7 times 18, which equals 126. Adding the new observation of 16 gives a new total sum of 142 for eight observations. Divide 142 by 8 to find the new mean. The new mean is 17.75.