D. None of these
Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?
If 8 men can reap 80 hectares 24 days, then how many hectares can 36 men reap in 30 days?
7 person can do a piece of work in 21 days. How many persons are required to do a piece of work in 3 days?
A, B and C start at the same time in the same direction to run around a circular stadium. A completes a round in 252 seconds, B in 308 seconds and C in 198 seconds, all starting at the same point. After what time will they meet again at the starting point?
A and B working together can finish a job in T days. If A works alone and completes the job, he will take T+5 days. If B works alone and completes the same job, he will take T+45 days. What is T?
Two pipes A and B can fill a cistern in 12 minutes and 16 minutes respectively. If both the pipes are opened together, then after how much time B should be closed so that the tank is full in 9 minutes?
12 buckets of water fill a tank when the capacity of each tank is 13.5 litres. How many buckets will be needed to fill the same tank, if the capacity of each bucket is 9 litres?
9 examiners can examine a certain number of answer books in 12 days by working 5 hours a day. How many hours in a day should 4 examiners work to examine twice the number of answer books in 30 days?
A and B can do a work in 10 days. B and C in 12 days while C and A in 15 days. How long would they take if all the three work together?
30 laborers, working 7 hours a day can finish a piece of work in 18 days. If the laborers work 6 hours a day, then the number of laborers to finish the same piece of work in 30 days, will be: