Time & Work (Negative Work)

1) Aman can build a wall in 15 days, and Bharat can build it in 10 days, but Chintu can destroy it in 30 days. If they all work together, how long will it take to complete the wall?

2) Pipe A fills a tank in 12 hours, and Pipe B fills it in 18 hours, while a leakage can empty it in 36 hours. If all are opened together, how long will it take to fill the tank?

3) A group of workers can dig a pit in 25 days, while another group can do the same in 30 days. But a refilling machine refills it in 75 days. How long will it take to dig the pit?

4) A pipe can fill a tank in 20 minutes, while another fills it in 30 minutes. A third pipe empties it in 40 minutes. If all pipes are opened together, how long will it take to fill the tank?

5) A road construction team can complete a road in 50 days, and another team can complete it in 75 days, but a natural erosion process removes 1/150 of the road daily. If all happen together, how long will it take to finish the road?

6) A bricklayer lays a wall in 15 days, another in 20 days, and a storm damages it in 60 days. If all act together, how long will the wall take?

7) A pipe fills a tank in 9 hours, another in 12 hours, while a leak empties it in 36 hours. How long will it take to fill the tank?

8) One painter paints a house in 20 days, another in 30 days, while rain washes paint off at 1/60 rate per day. How long will painting take?

9) A machine produces 500 items/day, another produces 400/day, but 100 items are defective each day. How many days to produce 3000 items?

10) A writer completes a book in 40 days, another in 50 days, while an editor removes 2 pages/day. How long to complete a 200-page book?

11) A team can repair a road in 12 days, while another team takes 18 days. But daily traffic damage adds 1/36 of the road's damage per day. How long will it take to repair the road?

12) A reservoir is filled by a pipe in 20 hours and another in 25 hours. Evaporation removes 1/50 of the water every hour. How long to fill the reservoir?

13) A builder constructs a house in 60 days, another in 80 days, while storms damage 1/120 of the house daily. How long will it take to build?

14) A team repairs a bridge in 45 days, another in 60 days, while river currents damage 1/90 per day. How long will it take to repair?

15) A group cleans a pond in 30 days, another in 40 days, but algae grow back at a rate of 1/120 per day. How long to clean the pond?

16) A gardener removes weeds in 16 days, another in 24 days, but weeds regrow at a rate of 1/48 per day. How long to clear weeds?

17) One person mows a lawn in 5 hours, another in 7 hours, but grass regrows at 1/14 per hour. How long to mow?

18) A printer prints in 8 hours, another in 12 hours, but paper jams delay printing by 1/24 per hour. How long to print all pages?

19) A person picks fruit in 10 hours, another in 15 hours, while birds eat 1/30 of the fruit per hour. How long to pick all fruit?

20) One worker cleans a park in 20 days, another in 25 days, but visitors litter at 1/50 per day. How long to clean the park?