Question

In $12$ days, the earth picks up $1.8\times {10}^{8}Kg$ of dust from the atmosphere. In how many days it will pick up $7.2\times {10}^{8}Kg$ of dust?

Answer 1

amount of dust picked by earth in $12$ days $=1.8\times {10}^{8}kg$

amount picked in $1$ day = $\frac{1.8\times {10}^8}{12}=\frac{3}{2}\times {10}^{7}kg$

$=1.5\times {10}^{7}kg$

no. of days taken to pick $72\times {10}^{8}kg$ of dust $=\frac{7.2\times {10}^8}{1.5\times {10}^7}$

$=\frac{72}{1.5}$

$\therefore$ Earth takes $48$ days to pick up $7.2\times {10}^{8}kg$ dust.