Pradeep's age is 15 and his father's age is 40. We record the ages of both of them every 2 years from now. As pradeep's age increases with his father's age, both the readings are in direct proportion.
Let the age of Pradeep be P and his father’s age be F
Even though Pradeep’s age increases with his father, if we calculate the ratio P/F, it wil not be constant. Hence, both the readings are not in direct proportion.