Exams › SSC CGL (Prelims) › General

The ratio of the times taken by X and Y to complete a task is $5:3$. If Y alone takes 15 hours, how long will X and Y together take?

1. 8.5 hrs
2. 9.375 hrs
3. 10 hrs
4. 11 hrs

Correct answer: 9.375 hrs

Solution

Since time is inversely proportional to work rate, X:Y time ratio $=5:3$ means X:Y efficiency ratio $=3:5$. If Y takes 15 hours, X takes $15\times \frac{5}{3}=25$ hours. Together their rate is $1/25+1/15=8/75$, so time taken is $75/8=9.375$ hours.

Related SSC CGL (Prelims) General questions

• P and Q together can complete a job in 16 days. Q and R together can complete it in 24 days, and R and P together can do it in 32 days. In how many days can P alone complete the job?
• X can complete a project in 14 days and Y in 10 days. When Z joins them, the work is finished in 3.5 days. How many days would Z need alone?
• P can complete a task in 6 days, and Q can destroy it in 4 days. P works for 3 days, then Q joins for 2 days. In how many days will P finish the remaining work alone?
• A traveller goes from City P to Q at 24 km/h in 5 hours. By how much should the speed be increased to complete the journey in 3 hours?
• X can do a job in 10 days, and Y can do it in 15 days. They work together for 4 days. What fraction of the work remains?
• X and Y complete a task in 14 days, and Y and Z complete it in 18 days. If X works for 6 days, Y for 8 days, and Z for 12 days to complete the task, how many days will Z alone take approximately?

⚔️ Practice SSC CGL (Prelims) General free + battle 1v1 →