Math 2022 Question 35
2 Marks
Question
The mean of four numbers was 80. When one number was removed the mean remained 80.
Explain how this was possible.
Answer
The number that was removed was 80. Therefore it would not affect the mean when removed.
Explanation
The mean is the average. Therefore if the mean of 4 numbers is 80 it means the total is = 4×80 = 320
If we remove 80 from it we now have 3 numbers. The total would be 320-80 = 240.
The average of 3 numbers would be 240/3 = 80.
Therefore if the same number is removed the average/mean would not change.
