Question

the average of 3 numbers is 9. if two of the numbers are 7 n 9. the third number is​

Answer 1

Answer :-

Third Number = 11.

Explanation :-

Given :

• Average of 3 numbers = 9.
• Two numbers are 7 and 9.

To Find :

• Third Number.

Solution :

Let the Third Number be x.

We know that,

Mean/Average :-

Sum of Observations/No. of Observations.

Substitute the Values.

➝ 9 = (7 + 9 + x)/3.

➝ 9 = (16 + x)/3.

➝ 9(3) = 16 + x.

➝ 16 + x = 27.

➝ x = 27 – 16.

➝ x = 11.

Therefore, Third Number = 11.

Verification :

➝ 9 = (7 + 9 + x)/3.

➝ 9 = (16 + 11)/3.

➝ 9(3) = 27.

➝ 27 = 27.

LHS = RHS.

Hence, Verified.