Find the mean of i the first eight natural numbers ii the first ten odd numbers iii the first seven ...

Question

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

Accepted Answer

i We know that First eight natural numbers 1 2 3 4 5 6 7 and 8 So we get Mean sum of numbers total numbers By substituting the values Mean 1 2 3 4 5 6 7 88 On further calculation Mean 368 By division Mean 45 Therefore the mean of the first eight natural numbers is 45 ii We know that First ten odd numbers 1 3 5 7 9 11 13 15 17 and 19 So we get Mean sum of numbers total numbers By substituting the values Mean 1 3 5 7 9 11 13 15 17 1910 On further calculation Mean 10010 By division Mean 10 Therefore the mean of first ten odd numbers is 10 iii We know that First seven multiples of five 5 10 15 20 25 30 and 35 So we get Mean sum of numbers total numbers By substituting the values Mean 5 10 15 20 25 30 357 On further calculation Mean 1407 By division 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 So we get Mean sum of numbers total numbers By substituting the values Mean 1 2 4 5 10 206 On further calculation Mean 426 By division Mean 7 Therefore the mean of all the factors of 20 is 7 v We know that All prime numbers between 50 and 80 53 59 61 67 71 73 and 79 So we get Mean sum of numbers total numbers By substituting the values Mean 53 59 61 67 71 73 797 On further calculation Mean 4637 So we get Mean 6617 Therefore the mean of all prime numbers between 50 and 80 is 6617

RS Aggarwal Solutions Class 9 Mathematics Solutions for Mean Median And Mode Of Ungrouped Data Exercise 18A in Chapter 18 - Mean Median And Mode Of Ungrouped Data