Question

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

• A. $9\frac{1}{3}days$
• B. $11days$
• C. $12\frac{1}{4}days$
• D. $16\frac{1}{2}days$

Answer 1

Answer: (B)

$11days$

$A$ and $B$ can do a job together in 7 days $A$ is $1\frac{3}{4}$ times as efficient as $B$

$\begin{array}{cc}\Rightarrow A:B& =\mid \frac{3}{4}:1\\ & =7:4\\ A& =7x,B=4x\end{array}$

$\underset{–}{A\cdot T\cdot Q}$

$\begin{array}{c}A+B=\frac{1}{7}\\ 7x+4x=\frac{1}{7}\\ \Rightarrow x=\frac{1}{77}\\ \therefore A=7x=\frac{1}{11}=11\text{days}\end{array}$

Hence, (B) is the correct option.