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Practice Time 12C

1. Joseph and Peter can weed a certain field in 6 days and 12 days respectively. If they work together
in how many days will they weed the field?
2. Archana can finish a work in 16 hours and Chetna can do the same work in half the time taken by
Archana. If they work together what part of the same work they can finish in 2 hours?
3. A and B together can do a piece of work in 15 days, while B alone can finish it in 25 days. In how
many days can A alone finish the work?
4. X and Y can do a piece of work in 36 days. Y and Z can do it in 48 days. X and Z can do it in 60 days.
Find the time taken by X, Y, and Z separately to finish the work.
5. A can do a piece of work in 10 days, and B in 20 days. They begin together but B leaves 3 days before
the completion of the work. In how many days will the whole work be completed?
6. A cistern can be filled by two taps P and Q in 15 hours and 18 hours respectively. The full cistern
can be emptied by a third tap R in 12 hours. All the taps are turned on at the same time. Find how
much time will they take to fill the empty tank completely.

7. A train running at the speed of 60 km/h. It crosses a pole that is in the way in 9 seconds. What is
the length of the train?

8. The speed of a train is 72 km/h which is 300 m long. How much time will it take to pass (a) an electric
pole, (b) a platform 400 m long?

9. A jogger running at a speed of 9 km/h alongside a railway track is 240 m ahead of the engine of
120 m long train running at 45 km/h in the same direction. In how much time will the train pass
the jogger?

10. Two trains are moving in opposite directions at a speed of 60 km/h and 90 km/h respectively. Their
lengths are 1.10 km and 0.9 km respectively. Calculate the time taken (in s) by them to cross each
other.

Mental Maths
1. In each of the following cases, tell whether the two quantities vary directly or indirectly (inversely)
with each other or neither of the two.

(a) x 0.5 2 8 32 (b) p 1 2 2 2 3 2 4 2
y 2 8 32 128 q 1 3 2 3 3 3 4 3

(c) r 2 5 10 25 50 (d) u 2 4 6 9 12
s 25 10 5 2 0.5 v 18 9 6 4 3
2. Both x and y vary directly with each other, and when x is 10, y is 14. Write any three possible pairs of
corresponding values of x and y.
3. Both m and n vary inversely with each other, and when m is 8, n is 15. Write any three possible pairs of
corresponding values of m and n.
4. A car is travelling 48 km in one hour. How much distance will the car travel in 12 minutes?
5. An autorickshaw takes 3 hours to cover a distance of 36 km. If its speed is increased by 4 km/h, the time taken
by it to cover the same distance is ............... .
2
6. If the area occupied by 15 postal stamps is 60 cm , then find the area occupied by 120 such postal stamps.
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