Time and Work Questions

S does half as much work as T in 1/7 of the time taken by T. If together they take 21 days to complete a work, then how may days shall S take to complete that work alone?

Prahlad has done 1/3rd of a job in 30 days, Sarfaraz completes the rest of the job in 90 days. In how many days can they together do the job?

Makarand works 2 times as fast as Samarjit. If Samarjit can complete a job alone in 27 days, then in how many days can they together finish the job?

20 boys do one fourth of work in 25 days. How many more boys will be required to complete the remaining work in 50 days?

Ajay can do a painting in 12 days. Amit is 70% more efficient than Ajay. What is the number of days Amit would need to finish the same painting?

P and Q can do a project in 12 and 12 days respectively. In how many days can they complete 50% of the project if they work together?

M can complete 3/4 part of a work in 12 days and N can complete 2/7 part of the same work in 8 days. In how many days will both complete 11/14 part of the total work?

Pramod can paint a wall red in 12 hours while Brajen can whitewash the wall completely in 16 hrs. If Pramod and Brajen work alternately for an hour each starting when the wall has just cement on it till when it is completely painted red, how many hours will it take to paint the entire wall red?