Question

Average of three person’s age is 9 years. Find the sum of there age.
A. 18
B. 21
C. 24
D. 27

Answer 1

HOLA

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$sum \: of \: age \: = \: ( \: \alpha \: + \: \beta \: ) \\ \\ sum \: of \: age \: = \: ( \: 9 \: + \: 9 \: ) \: = \: 18$
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Option A

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HOPE U UNDERSTAND ❤❤

Answer 2

Concept-

Average is defined as the ratio of the sum of the quantities to the number of quantities.

Average = Sum of all the quantities / Number of quantity

Given-

Average age of three persons is 9 years.

Find-

Find the sum of the the age of three persons.

Solution-

Average age = x1 + x2 + x3 + x4..........+ xn / N

Let the age of three persons be x years, y years and z years.

Now, the average age of these three persons is 9.

Average = (x + y + z)/3

9 = (x + y + z) / 3

27 = x + y + z

So, the sum of three persons ages is 27.

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