II. Let the present ages of Arun and his son be 11x and 6x years respectively.

I. 5 years ago, Arun’s age = 2 x His son’s age.

III. 5 years hence,

Clearly, any two of the above will give Arun’s present age.

 Correct answer is (D).

  I. Let Ravi’s present age be x years. Then, his father’s present age = 2x years.

II. After 5 years,

III. Ravi is younger than his brother.

From I and II, we get This gives x, the answer.

Thus, I and II together give the answer. Clearly, III is redundant.

 Correct answer is (A).

  I. Let the present ages of Tanya and Rahul be 3x years and 4x years.

II. After 5 years, (Tanya’s age) : (Rahul’s age) = 4 : 5.

III. (Rahul’s age) = (Tanya’s age) + 5.

From I and II, we get  This gives x.

 Tanya’s age = 3x can be found. Thus, I and II give the answer.

From I and III, we get 4x = 3x + 5. This gives x.

 Tanya’s age = 3x can be found. Thus, I and III give the answer.

From III : Let Tanya’s present age be t years.

Then Rahul’s present age = (t + 5) years.

Thus, from II and III, we get : This gives t.

Thus, II and III give the answer.

 Correct answer is (E).