Saturday, 13 August 2011

CBSE NCERT CLASS 8 MATH :UNITARY METHOD/VARIATION


   Q1.
12 men can repair a road in 28 days. how long will 84 men take to do so?


Q2.
8 taps having the same rate of flow, fill a tank in 27minutes. If two taps go out of order, how long will the remaining taps take to fill the tank?

Q3.
15pumps can empty a reservoir in 24hours. In how many hours can 45such pumps do the same work?

Q4.
4people can finish a piece of work in 6hours; how many can do it in 4hours?

Q5.
20 men produce 3000 articles in 12days. How long should 15men take?

Q6.
12men can dig a pond in 8days. How many men can dig it in 6days?

Q7.
A car can finish a certain journey in 9 hrs. the speed of 72km/h. By how much should its speed be increased so that it may take only 8hto cover the same distance?

Q8.
A garrison of 500 men had provision for 24days. However a reinforcement of 300men arrived. Now for how many days the food will last?

Q9.
If 36men can do a piece of work in 25days, in how many days can 15men do it?

Q10.
If 32men can reap a field in 15days, in how many days can 20men reap the same field?

Q11.
If the cost of 13m of plastic rope is Rs84.50, then what would it cost to buy 50mof such plastic rope?

Q12.
20 stamps of equal value cost Rs24. How many stamps of the same value can be bought for Rs 60?

Q13.
A machine takes 7 hours in cutting 168 tools. How many tools will it cut in 25hours?

Q14.
If x and y very directly and y=20 when x =4, find y when x=6.

Q15.
20 iron rods of the same size weigh 240kg. What will be the weight of 42 such iron rods?

Q16.
On a particular day, 200US dollars are worth Rs9666. On that day, how many dollars could be bought for Rs5074.65?

Q17.
If a car covers 102km in 6.8litresof petrol, how much distance will it cover in 24.2litresof petrol?

Q18.
If a man earns earns Rs805per week. In how many days he will earn Rs2070?

Q19.
A train covers 85km in 112h. Assuming that the speed of the train remains uniform, find the time required to cover a distance of 204km.

Q20.
If 8oranges cost Rs10.40, how many oranges can be bought for Rs33.8

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