Question

The average of some natural numbers is 15. If 30 is added to first number and 5 is subtracted from the last number the average becomes 17.5 then the number of natural number is

• A. 20
• B. 10
• C. 30
• D. 15

Answer 1

Answer:

B. 10

Number of natural numbers = x sum = 15x 15x + 30 – 5 = x × 17.5 17.5x – 15x = 25 ⇒ 2.5x = 25 x =10