Answer: Option A
:
Steps: 2 Mark
Answer: 1 Mark
Given that
Mohan finishes the work in $\frac{7}{12}$ of an hour.
Also given that
Keerthi finishes the work in $\frac{3}{4}$ of an hour.
Now, $\frac{7}{12}$ of an hour
$\Rightarrow \frac{7}{12}\times 60minutes$
$\Rightarrow 35mins$
Again
$\frac{3}{4}$ of an hour
$\Rightarrow \frac{3}{4}\times 60$
$\Rightarrow 45minutes$
Clearly, Keerthi worked more by 45 - 35 = 10 more minutes.
Now, when expressed as a fraction
$\frac{10}{60}=\frac{1}{6}$ of an hour.
Alternative Way
Method II
Now, $\frac{7}{12}and\frac{3}{4}$
Making them Like fractions we have
$\frac{7\times 1}{12\times 1}\&\frac{3\times 3}{4\times 3}$
i.e. $\frac{7}{12}<\frac{9}{12}$
Clearly, Keerthi who takes ${\frac{3}{4}}^{th}$ of an hour takes longer than Mohan who takes ${\frac{7}{12}}^{th}$ of an hour.
So, subtracting we have
$\frac{9}{12}-\frac{7}{12}=\frac{2}{12}=\frac{1}{6}$ of an hour.