Answer: Option C
Answer: (c)Using Rule 1, Average of two or more numbers/quantities is called the mean of these numbers, which is given by$\text"Average(A)" = \text"Sumof observation / quantities"/\text"No of observation / quantities"$∴ S = A × nAccording to question, The average of 9 numbers = 30 Now,The total of 9 numbers = 30 × 9 = 270 The average of first 5 numbers = 25 ∴ The total of first 5 numbers = 25 × 5 = 125 and Total of last 3 numbers = 3 × 35 = 105 Hence, required answer = 270 – (125 + 105) = 270 – 230 = 40