Page 91 - New Medley 5 Semester 2

Sum = 10 + 2 + 9 = 21 L
10 L 2 L
Number of values = 3

9 L 21
Average = = 7 L
3

Sum = 5 + 8 + 7 + 6 = 26 cm
5cm 8cm
Number of values = 4

7cm 6cm 26
Average = = 6.5 cm
4

Thus, we observe that

  Average may be exactly same as an observation given in the collection.

  Average may be different from all the observations.
  Average is not always a whole numbers.

Example 7: Find the average of first six multiples of 3.

Solution: First six multiples of 3 are 3, 6, 9, 12, 15 and 18.

Sum of the multiples = 3 + 6 + 9 + 12 + 15 + 18 = 63

63
\ Average = = 10.5
6

Example 8: The average of three numbers is 12. If two numbers
out of three are 6 and 15, find the third number.

Solution: Since average of three numbers = 12

So, sum of three numbers = 12 × 3 = 36

The two numbers are 6 and 15 respectively.

 The third number = 36 – (Sum of two numbers)

= 36 – (6 + 15)

= 36 – 21 = 15

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