The mean: balance point and fair share
Answers are for parents and teachers.
1
Find the mean of 7, 9, 12, 8, 14.
The total is 50 and 50 ÷ 5 = 10.
2
Five pupils have 3, 7, 4, 9 and 2 books. Level them out. How many books does each pupil get?
3 + 7 + 4 + 9 + 2 = 25 and 25 ÷ 5 = 5 books each.
3
Rana has scored 6, 8 and 7 in three games. How many must she score in the fourth game for the mean to be 8?
The total must be 8 × 4 = 32. So far 6 + 8 + 7 = 21. She needs 32 − 21 = 11.
4
Use distances to show that 7 is the balance point of 5, 5, 6, 8, 11.
Left of 7: 2 + 2 + 1 = 5. Right of 7: 1 + 4 = 5. The totals are equal.
5
The mean of five numbers is 20. A sixth number, 8, is added. Is the new mean larger or smaller than 20? Find it.
Smaller, because 8 is below the mean. The total was 100, now 108, and 108 ÷ 6 = 18.