In 15 days, the earth picks up 1.2 x `10^8` kg of duct from the atmosphere. In how many days it will pick up 4.8 x `10^8` kg of dust?

Explanation

Let `x` be the number of days taken by the earth to pick up `4.8×10^8` kg.
Since, the amount of dust picked up by the earth and the number of days are in direct variation, we get:
`⇒ 15/x=(1.2 xx 10^8)/(4.8 xx 10^8)`
`⇒ x=60`
∴ The required number of days will be `60`.