Multiple choice

The marks obtained by 5 students are 21, 27, 19, 26, and 32. Later on 5 grace marks are added to each students. What are the average of the revised marks of the students?

  1. 26

  2. 30

  3. 31

  4. 32
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The average of a set of numbers increases by the same amount as the constant added to each number. Since 5 is added to each of the 5 marks, the original average of 25 increases by 5 to become 30.

AI explanation

The formula for average is the total sum of all values divided by the count of values, so the original average is (21 + 27 + 19 + 26 + 32) / 5 = 125 / 5 = 25. According to the properties of averages, if a constant number is added to each item in a data set, the overall average increases by that same constant. Therefore, adding 5 grace marks to each of the 5 students increases the average by 5, making the new average 25 + 5 = 30.

Keep practicing — related questions