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सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

A and B Working Together Can Do a Piece of Work in 10 Days B Alone Can Do the Same Work in 15 Days. How Long Will a Alone Take to Do the Same Work ?

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प्रश्न

A and B working together can do a piece of work in 10 days B alone can do the same work in 15 days. How long will A alone take to do the same work?

बेरीज
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उत्तर

A and B working together can do a piece of work in 10 days

and B alone can do the same work in 15 days

A and B's one day's work = `1/10`

and B's one day's work = `1/15`

∴ A's one day's work = `1/10 - 1/15`

`= (3 - 2)/30 = 1/30`

Hence A can do the same work in = 30 days

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पाठ 7: Unitary Method (Including Time and Work) - Exercise 7 (C)

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सेलिना Concise Mathematics [English] Class 7 ICSE
पाठ 7 Unitary Method (Including Time and Work)
Exercise 7 (C) | Q 2

संबंधित प्रश्‍न

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:

(i) how much work can A do in 1 hour ?
(ii) how much work can B do in 1 hour ?
(iii) in how much time will the work be completed, if both work together.


A, B and C together finish a work in 4 days. If A alone can finish the same work in 8 days and B in 12 days, find how long will C take to finish the work.


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A boy drives his scooter with a uniform speed of 45 km/h. Find the time taken to cover 900 m.


A man walks a distance of 5 km in 2 hours. Then he goes in a bus to a nearby town, which is 40 km, in further 2 hours. From there, he goes to his office in an autorickshaw, a distance of 5 km, in `1/2` hour. What was his average speed during the whole journey?


Jagan went to another town such that he covered 240 km by a car going at 60 kmh-1. Then he covered 80 km by a train, going at 100 kmh-1 and the rest 200 km, he covered by a bus, going at 50 kmh-1. What was his average speed during the whole journey?


Anbarasan travelled 350 Km at the speed of 70 Km/hour. Find the time taken for his travel


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

What is the correct relationship between speed (S), distance (D), and time (T)?


The SI unit of speed is:


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