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131. A and b worked on a job for 4 hrs and finished half of it. A worked thrice as fast as b did. If b then left a and was joined by c and they finished the job in 1 hour , how long it would have taken for c to do the whole job alone?

132. Pipes a and b can fill a cistern in 20 min and 30 min and c can empty it in 15 min. If the three are kept open successively for 1 min each in the order how soon will the cistern be filled?

133. A and b can fill a cistern in 15/2 min and 5 min and c can carry of 14 litres per minute. If all pipes are open when it is full , it is emptied in 1 hours. How many litres can it hold?

134. In what time would a cistern be filled by three pipes whose diameter are 1 cm , 4/3cm, 2 cm running together.. When the largest alone will fill it in 61 minutes; the amount of water flowing in by each pipe being proportional to the square of its diameter?

135. Three men can do as much work as 5 boys and the wages of 3 boys are equal to those of 2 men. A work on which 40 boys and 15 men are employed takes 8 weeks and costs rs 15750. How long would it take if 20 boys and 20 men were employed , and how much would it costs?

136. A,B and C can do a piece of work in 12,18, and 24 days respectively. They work at it together . A stops the work after 4 days and B is called off 2 days before the work is done.in what time was the work finished?

137. If a can do as much work in 4 hours as b can do in 6 hours, or as c can do in 8 hours how long will it take c to complete a piece of work , one third of which has been done by a working 8 hours and b working 18 hours?

138. If a can do as much work in 4 hours as b can do in 8 hours, how long will it take c to complete a piece of work , one third of which has been done by a working 8 hours and b working 18 hours?

139. C does half as much in a day as a and b can do together, and b does half as much again as a. If all there working together can mow 20 hectares of barely in 16 days, how long would each , working by himself take to mow 5 hectares?

140. If 15 men or 24 women or 36 boys can do a piece of work in 12 days working 8 hours a day , how many men must be associated with 12 women and 6 boys to do another piece of work 9/4 times as great in 30 days working 6 hrs/ day?