Question:
Ravi can do a piece of work in 15 hours while Raman can do it in 12 hours. How long will both take to do it, working together?
Solution:
Time taken by Ravi $=15 \mathrm{~h}$
Time taken by Raman $=12 \mathrm{~h}$
Work done per hour by Ravi $=\frac{1}{15}$
Work done per hour by Raman $=\frac{1}{12}$
Work done per hour by Ravi and Raman together $=\frac{1}{15}+\frac{1}{12}=\frac{9}{60}=\frac{3}{20}$
$\therefore$ Time taken by Ravi and Raman together to finish the work $=\frac{20}{3} \mathrm{~h}=6 \frac{2}{3} \mathrm{~h}$
Click here to get exam-ready with eSaral
For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.