Q315
A can do piece of work in 15 days. B is 25% more efficient than A, and C is 40% more efficient than B, A and C work together for 3 days and then C leaves. A and B together will complete the remaining work in:
A.
3 days
AnswerB.
C.
4 days
D.
Answer: Option A
Solution
Answer: Option A
Solution:
\begin{array}{*{20}{c}}
{}&\begin{gathered}
{\text{A}}\,\,\,\,\,\,{\text{B}}\,\,\,\,\,\,{\text{C}} \hfill \\
{\text{4}}\,\,\,{\text{:}}\,\,\,{\text{5}}\,\,\,{\text{:}}\,\,\,{\text{7}} \hfill \\
{\text{5}}\,\,\,{\text{:}}\,\,\,{\text{7}}\,\,\,\,\,\,\,\,\,\, \hfill \\
\end{gathered} \\
{{\text{Efficiency}} \to }&{\overline {\,4\,:\,5\,:\,7\,} }
\end{array}Total work = 4 × 15 = 60 units
(A + C) × 3 + (A + B)x = 60
11 × 3 + 9 × x = 60
33 + 9x = 60
9x = 27
x = 3 days