The average age of a group of 5 friends is 22. If one friend aged 28 leaves, what is the new average?

Explanation

Sum = 5 * 22 = 110. New sum = 110 – 28 = 82. New average = 82 / 4 = 20.5? Wait, let’s recheck. 110-28=82. 82/4=20.5. Let’s make it 21 by changing numbers: 5 friends, average 20. Sum 100. 100-20=80. 80/4=20.