Question

It takes $15minutes$ a cup to be $one-fourth$ full. How much time will it take to fill the cup?

Answer 1

Time taken by cup to be $one-fourth$full.

So, in $15minutes$ cup will be $\frac{1}{4}thfull$

in next $15minutes$ i.e., in $30minutes$ , cup will be $(\frac{1}{4}+\frac{1}{4})=\frac{1}{2}full$

Hence , in $(30+30)minutesi.e.,60minutes$ to fill the cup.