Page 3 - Lesson note-5-Ch 14 Statistics ( Measure of Central Tendency)

Example 3. Find the mean of:
(i) the first eight natural numbers
(ii) the first ten odd numbers
(iii) the first seven multiples of 5
(iv) all the factors of 20
(v) all prime numbers between 50 and 80.

(i) We know that
First eight natural numbers = 1, 2, 3, 4, 5, 6, 7 and 8
Mean = sum of numbers/ total numbers

Mean = (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8)
8
36
Mean =
8
Mean = 4.5

(ii) We know that First ten odd numbers = 1, 3, 5, 7, 9, 11, 13, 15, 17 and 19
Mean = sum of numbers/ total numbers
Mean = (1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19)/10
Mean = 100/10
Mean = 10
Therefore, the mean of first ten odd numbers is 10

(iii) We know that First seven multiples of 5 = 5, 10, 15, 20, 25, 30 and 35
Mean = sum of numbers/ total numbers
Mean = (5 + 10 + 15 + 20 + 25 + 30 + 35)/7
Mean = 140/7
Mean = 20
Therefore, the mean of first seven multiples of five is 20.

(iv) We know that
All the factors of 20 = 1, 2, 4, 5, 10 and 20
Mean = sum of numbers/ total numbers
Mean = (1 + 2 + 4 + 5 + 10 + 20)/6
Mean = 42/6