Multiple choice general knowledge math & puzzles

The average age of 20 boys in a class is 14. If the teacher is included in the group and one boy is excluded from the group, the average increases by 0.5. What is the difference in the age of the teacher & the out going student

  1. 41

  2. 45

  3. 32

  4. 20

  5. None of these

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

Total age of 20 boys = 280. New group (19 boys + 1 teacher) average is 14.5. Total new age = 20 * 14.5 = 290. (Teacher - Boy) = 290 - 280 + (Boy - Boy) = 10? No, (Sum - Boy + Teacher)/20 = 14.5 => 280 - B + T = 290 => T - B = 10. None of the numerical options match.