Q1 of 41 Page 11

Explain the concept of direct variation.

In case of direct variation both the quantities vary in the ratio i.e if one quantity is doubled then other will also get double. If one quantity gets half the other will also get half.


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2

Which of the following quantities vary directly with each other?

(i) Number of articles (x) and their price (y)


(ii) Weight of articles (x) and their cost (y).


(iii) Distance x and time y, speed remaining the same.


(iv) Wages (y) and number of hours (x) of work.


(v) Speed (x) and time (y) distance covered remaining the same).


(vi) Area of a land (x) and its cost (y).

 3

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


 4

Fill in the blanks in each of the following so as to make the statement true:

(i) Two quantites are said to very _______ with each other if they increase (decrease) together in such a way that the raio of the corresoponding values remains same


(ii) x and y are said to very directly with each if for some positive number k, _______ = k.

 5

Complite the following tables given that x varies directly as y.

(i)


















X



2.5



……….



……….



15



Y



5



8



12



……….



(ii)






















X



5



……



10



35



25



…….



Y



8



12



….



…….



…….



32



(iii)




















X



6



8



10



…….



20



Y



15



20



….



40



…….



(iv)






















X



4



9



……



…….



3



….



Y



16



…..



48



36



……



4



(v)


















X



3



5



7



9



2



…..



20



28



……