Banking Quantitative Aptitude Sample Paper Quantitative Aptitude Sample Paper-45

If A and B together can finish a piece of work in 20 days, B and C in 10 days and C and A in 12 days, then A, B, C jointly can finish the same work in

A) \[4\frac{2}{7}\,\,\text{days}\]

B) \[30\,\,\text{days}\]

C) \[8\frac{4}{7}\,\,\text{days}\]

D) \[\frac{7}{60}\,\,\text{days}\]

Correct Answer: C

Solution :

According to the question,

(A + B)'s 1 day's work \[=\frac{1}{20}\] ... (i)

(B + C)'s 1 day's work \[=\frac{1}{10}\] ... (ii)

(C + A)'s 1 day's work \[=\frac{1}{12}\] ... (iii)

On adding Eqs. (i), (ii) and (iii), we get

\[A+B+B+C+C+A=\frac{1}{20}+\frac{1}{10}+\frac{1}{12}\]

\[\Rightarrow \]\[2\,(A+B+C)'=\frac{3+6+5}{60}=\frac{14}{60}=\frac{7}{30}\]

\[\therefore \](A + B + C)'s 1 day's work \[=\frac{7}{60}\]

Hence, the work will be completed in \[\frac{60}{7}=8\frac{4}{7}\]days.