• # question_answer In 15 days, the earth picks up $1.2\times {{10}^{8}}\text{kg}$ of dust from the atmosphere. In how many days it will pick up $4.8\times {{10}^{8}}\text{ kg}$of dust? A)  50                              B)         40      C)         60                              D)         100

 Number of days 15 x Weight of dust (in kg) $1.2\times {{10}^{8}}$ $4.8\times {{10}^{8}}$
More the dust, more the number of days it will take to pick it up. So, it is a case of direct proportion. $\therefore x=\frac{15}{1.2\times {{10}^{8}}}\times 4.8\times {{10}^{8}}days$ $\Rightarrow x=\frac{15\times 4.8}{1.2}=60days$