Question : X alone can complete a piece of work in 16 days, while Y alone can complete the same work in 24 days. They work on alternate days starting with Y. In how many days will 50% of the total work be completed?

Question : A can do a piece of work alone in 15 days, while B complete the same piece of work alone in 12 days. If they work on it together for 5 days, then the fraction of the work that will be left is:

Question : P, Q, and R alone can do a piece of work in 5, 6, and 4 days, respectively. All three of them began the work together but Q left 1 day before completion of the work. In how many days was the work completed?

Question : S alone can do a piece of work in 14 days. T alone can do the same work in 21 days. U alone can do the same work in 28 days. Working together, in how many days will they complete the work?

Question : $\mathrm{N}_1$ alone can do 20% of a piece of work in 6 days, $\mathrm{N}_2$ alone can do 20% of the same work in 4 days, and $\mathrm{N}_3$ alone can do 50% of the same work in 12 days. In how many days can they complete the work, if all of them work together?