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प्रश्न
Two taps can fill a cistern in 10 hours and 8 hours respectively. A third tap can empty it in 15 hours. How long will it take to fill the empty cistern, if all of them are opened together?
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उत्तर
First tap can fill a cistern in 10 hours
Second tap can fill the cistern in 8 hours
Third tap can empty the cistern in 15 hours
∴ First tap's 1 hour's work = `1/10`
Second tap's 1 hour's work = `1/8`
and third tap's 1 hour's work = `1/15`
If all of them are opened together, then
heir one hour's work = `1/10 + 1/8 - 1/15`
`= (12 + 15 - 8)/120 = (27 - 8)/120 = 19/120`
∴ They can fill the cistren in =`120/19` hours
`= 6 6/19` hours
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संबंधित प्रश्न
A can do a piece of work in 4 days and B can do the same work in 5 days. Find, how much work can be done by them working together in:
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What part of work will be left, after they have worked together for 2 days?
Joseph and Peter can complete a work in 20 hours and 25 hours respectively. Find :
(i) work done by both together in 4 hrs.
(ii) work left after both worked together for 4 hrs.
(iii) time taken by Peter to complete the remaining work.
A is able to complete `1/3` of a certain work in 10 hrs and B is able to complete `2/5` of the same work in 12 hrs. Find:
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A train covers 51 km in 3 hours. Calculate its speed. How far does the train go in 30 minutes?
A train travels 700 metres in 35 seconds. What is its speed in km/h?
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Look at the different types of boats.
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In one trip the logboat brings about 20 kg of fish. But other types of boats bring a bigger catch as given in the table. The table also shows the speed of each type of boat, which is how far each boat goes in one hour. Look at the table and calculate -
- About how much fish in all will each type of boat bring in seven trips?
| Type of boat | Catch of fish in one trip (in kg) |
Speed of the boat (how far it goes in one hour) |
| Log boat | 20 | 4 km per hour |
| Long tail boat | 600 | 12 km per hour |
| Motorboat | 800 | 20 km per hour |
| Machine boat | 6000 | 22 km per hour |
In one trip the logboat brings about 20 kg of fish. But other types of boats bring a bigger catch as given in the table. The table also shows the speed of each type of boat, which is how far each boat goes in one hour. Look at the table and calculate -
- About how far can a motorboat go in six hours?
| Type of boat | Catch of fish in one trip (in kg) |
Speed of the boat (how far it goes in one hour) |
| Log boat | 20 | 4 km per hour |
| Long tail boat | 600 | 12 km per hour |
| Motorboat | 800 | 20 km per hour |
| Machine boat | 6000 | 22 km per hour |
In one trip the logboat brings about 20 kg of fish. But other types of boats bring a bigger catch as given in the table. The table also shows the speed of each type of boat, which is how far each boat goes in one hour. Look at the table and calculate -
- If a long tail boat has to travel 60 km how long will it take?
| Type of boat | Catch of fish in one trip (in kg) |
Speed of the boat (how far it goes in one hour) |
| Log boat | 20 | 4 km per hour |
| Long tail boat | 600 | 12 km per hour |
| Motorboat | 800 | 20 km per hour |
| Machine boat | 6000 | 22 km per hour |
