Question

Babu and Asha can do a job together in 7 days. Asha is $1\frac{3}{4}$ times as efficient as Babu. The same job can be done by Asha alone in

• A. $\frac{49}{4}$ days
• B. $\frac{49}{3}$ days
• C. 11 days
• D. $\frac{28}{3}$ days

Answer 1

The correct option is C 11 days

If Babu can do a job in $x$ days, then Asha can do the same job in $\frac{4x}{7}$ days.
$\therefore$ (Asha and Babu)'s one day's job $=\frac{1}{x}+\frac{7}{4x}$
Also given, (Asha and Babu)'s one day's job $=\frac{1}{7}$
$\therefore \frac{1}{x}+\frac{7}{4x}=\frac{1}{7}\Rightarrow \frac{4+7}{4x}=\frac{1}{7}\Rightarrow x=\frac{77}{4}$
$\therefore$ Asha alone can do the job in $\frac{4}{7}\times \frac{77}{4}$ days $=11$ days.