In which of the following tables x and y vary directly?

(i)


A



7



9



13



21



25



B



21



27



39



63



75



(ii)


A



10



20



30



40



46



B



5



10



15



20



23



(iii)


A



2



3



4



5



6



B



6



9



12



17



20



(iv)


A



12



22



32



42



52



B



13



23



33



43



33


(i) Directly proportional.


Eplanation: 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.


Eplanation: 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.


Eplanation: 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.


Eplanation: 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.


3