P, Q and R can do a certain job in 10 hours, 12 hours and 15 hours, while working individually. To finish the job, they started working together in pairs. However, none of the pairs work for more than an hour at a stretch and none of the persons can work for more than 2 hours at a stretch. What is the least time by which the job will be finished ?

Marge has 3 pumps for filling her swimming pool. When all 3 pumps work at their maximum rates, the swimming pool is filled in 56 minutes. Pump 1's maximum rate is twice the maximum rate of pump 2 and four times the maximum rate of pump 3. How long would it take Marge to fill the pool if she used only pump 3 at its maximum rate ?

A chemical factory produces two kinds of unnatural amino acids: acid A and acid B. Of the acids produced by the factory last year, were acid A and the rest were acid B. If it takes as many hours to produce acid B per unit as it does to produce acid A per unit, then the number of hours it took to produce the acid B last year was what fraction of the total number of hours it took to produce all the acids?

Water has been poured into an empty rectangular tank at the rate of 5 cubic feet per minute for 6 minutes. The length of the tank is 4 feet and the width is of the length. How deep is the water in the tank? (1 foot = 12 inches)

Water is leaking out from a cylinder container at the rate of 0.31 m^3 per minute. 10 minutes later, the water level decreases 0.25 meter, what is value of the radius?

The ratio of Kim’s time to paint a house to Jane’s time to paint a house is 3 : 5. If Kim and Jane work together at their respective constant rates, they can paint a house in 10 hours. What is the number of hours it takes Kim to paint the house alone?

John has to hammer 100 railroad spikes for a new line his company is building. Working at a constant rate, he can hammer 8 spikes per hour. When he is halfway done, his coworker Paul begins working at the same constant rate. Compared to John completing all the work alone, how many hours are saved with Paul’s help?

Four men and three women can do a job in 6 days. When five men and six women work on the same job, the work gets completed in 4 days. How many days will a woman take to do the job, if she works alone on it?

One pipe can fill a pool 1.25 times faster than a second pipe. When both pipes are opened, they fill the pool in five hours. How long would it take to fill the pool if only the slower pipe is used?

If both valves are open simultaneously, they can fill an empty pool in 48 minutes. The first valve, when working independently, takes 2 hours to fill the pool. If the second valve releases 50 cubic meters of water more than the first valve every minute, what is the capacity of the pool?