(i) Directly proportional.
Explanation: In this table value of ‘b’ is thrice the value of ‘a’ in all the columns. Therefore ‘a’ and ‘b’ are directly proportional.
(ii) Directly proportional.
Explanation: In this table value of ‘b’ is half of the value of ‘a’ in all the the columns. Therefore ‘a’ and ‘b’ are directly proportional.
(iii) Not directly proportional.
Explanation: In this table value of ‘b’ is not thrice the value of ‘a’ in all the columns. Therefore ‘a’ and ‘b’ are not directly proportional.
(iv) Not directly proportional.
Explanation: In this table value of ‘b’ is not varying in the same ratio as the value of ‘a’ in all the columns. Therefore ‘a’ and ‘b’ are not directly proportional.