Time and Work Questions

Jaikishen can do a piece of work in 15 hours. If he is joined by Jhanvi who is 50% more efficient, in what time will they together finish the work?

A mason can build a wall in 18 hours. After 9 hours he takes a break. What fraction of the wall is yet to be built?

10 persons can do a job in X days. If 20 persons with twice the efficiency can do the same job in 5 days, then find the value of X?

A, B and C can do a job working alone in 12, 16 and 24 days respectively. In how many days they can do the job if they worked together?

Working together P, Q and R reap a field in 6 days. If P can do it alone in 10 days and Q in 24 days, in how many days will R alone be able to reap the field?

An hour-long test has 60 problems. If a student completes 30 problems in 25 minutes, then the required seconds he has taken on average for computing each of the remaining problems is

A can do a piece of work in 8 days and B can do it in 10 days seperately. How many days would it take for both A and B to finish the same work together?

A, B and C can finish a job working alone in 20, 30 and 60 days respectively. They all work together for 1 day, then A and B quit. How many days C working alone will take to finish the remaining part of the job?