Given: The average of 10 number is 6. Concept: Average = (Sum of all observation/number of observation) Calculation: Let the 10 number is a1,a2,a3 . . . a10 The average of 10 number is ⇒
(a1+a3+a3+...+a10)
10
According to the question ⇒
(a1+a3+a3+...+a10)
10
= 6 ⇒(a1+a3+a3+...+a10) = 60 . . . (1) Now, Each number is multiplied by 13, then the new number is 13a1,13a2,13a3...13a10 So, The average of the 10 new number is ⇒
(13a1+13a3+13a3+...+13a10)
10
⇒
[13(a1+a3+a3+...+a10)]
10
⇒ (13 × 60)/10 . . . from equation (1) ⇒ 78 The required average is 78.