Question

2. Find the mean of:
(1) first eight natural numbers
(iii) first five odd natural numbers
(v) all prime numbers between 20 and 40.
(ii) first six even natural numbers
(iv) all prime numbers upto 30​

Answer 1

Step-by-step explanation:

(i) The first eight natural numbers are 1, 2, 3, 4, 5, 6, 7, 8 ∴ Sum of these observations =1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36 and, number of their observations = 8 ∴ Required mean = 36/8 = 4.5

(ii) The first six even natural numbers are 1 = 2, 4, 6, 8, 10, 12 ∴Sum of these observations = 2, 4, 6, 8, 10, 12 = 42 and, number of their observations = 6 ∴ Required mean = 42/6 = 7

(iii) The first five odd natural numbers are = 1, 3, 5, 7, 9 ∴Sum of these observations =1 + 3 + 5 + 7 + 9 = 25 and, number of their observations = 5 ∴Required mean = 25/5 = 5

(iv) The all prime numbers upto 30 are 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 ∴Sum of these observations = 2 + 3 +5 + 7+ 11 + 13 + 17 + 19 + 23 +29 = 129 and, number of their observations = 10 ∴ Required mean = 129/10= 12.9

(v) All prime numbers between 20 and 40 are 23, 29, 31, 37 Sum of these observations = 23 + 29 + 31 + 37 = 120 . and, number of their observations = 4 ∴ Required mean = 120/4 = 30