Q23 of 41 Page 11

In 15 days, the earth picks up kg of dust from the atmosphere. In how many days it will pick up kg of dust?

Let the number of days is














Weight of dust (pounds)



1.2 × 108



4.8 × 108



Time (days)



15






On cross multiplication, we get




Therefore the number of days required to pick up the dust is 60 days


More from this chapter

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21

The anount of extension in an elastic spring varies directly with the weight hung on it, If a weight of 250 gm produces an extension of 3.5 cm, find the extension produced by the wight of 700 gm.

 22

In 10 days, the earth picks up pounds of dust from the atmosphere. How much dust will it pick up in 45 days?

 1

In which of the following tables x and y vary inversely:

(i)


















X



4



3



12



1



Y



6



8



2



24



(ii)


















X



5



20



10



4



Y



20



5



10



25



(iii)


















X



4



3



6



1



Y



9



12



8



36



(iv)


















X



9



24



15



3



Y



8



3



4



25


 2

It x and y vary inversely, fill in the following blanks:

(i)




















X



12



16



…..



8



…



Y



….



6



4



…….



0.25



(ii)


















X



16



32



8



128



Y



4



…..



…….



0.25



(iii)


















x



9



……



81



243



y



27



9



……



1