Five numbers are in an arithmetic progression with common difference 3. Find the average of these five numbers if the largest number is 40% more than the smallest number.

Question: Five numbers are in an arithmetic progression with common difference 3. Find the average of these five numbers if the largest number is 40% more than the smallest number.

Solution:
Let,
The five numbers will be x, x + 3, x + 6, x + 9, x + 12

ATQ,
x × (140/100) = x + 12
⇒ 7x = 5x + 60
⇒ 2x = 60
∴ x = 30

∴ The numbers are = 30, 33, 36, 39, 42

∴ The average of the five numbers = (30 + 33 + 36 + 39 + 42)/5 = 180/5 = 36