Question : B and C can complete work alone in 10 days and 30 days respectively. They began the work together but B left the work after some days and C completed the remaining work in 10 days. After how many days from the beginning B left the work?
Option 1: 4 days
Option 2: 6 days
Option 3: 8 days
Option 4: 5 days
Correct Answer: 5 days
Solution :
Let the number of days they worked together be $x$
According to the question
⇒ The efficiency of B = $\frac{1}{10}$
⇒ The efficiency of C = $\frac{1}{30}$
Combined efficiency = $\frac{1}{10}$ + $\frac{1}{30}$ = $\frac{4}{30}$
⇒ Work done for $x$ days = $\frac{4x}{30}$
Remaining work = 1 – $\frac{4x}{30}$ = $\frac{30 – 4x}{30}$
⇒ The remaining work to be done by C in 10 days = $\frac{10}{30}$
⇒ $\frac{30 – 4x}{30}$ = $\frac{10}{30}$
⇒ 30 – 4$x$ = 10
⇒ – 4$x$ = 10 – 30
⇒ $x$ = $\frac{-20}{-4}$ = 5
Hence, the correct answer is 5 days.
Related Questions
Know More about
Staff Selection Commission Multi Tasking ...
Answer Key | Cutoff | Selection Process | Preparation Tips | Eligibility | Application | Exam Pattern
Get Updates Brochure
Your Staff Selection Commission Multi Tasking Staff Exam brochure has been successfully mailed to your registered email id “”.
