Direct and Inverse Proportions-Sample Questions

1.   A contractor estimates that 5 persons complete a task in 4 days. If he uses 4 persons instead of 5, how long should they take to complete the task?

2.   A school has 9 periods a day each of 50 minutes duration. How many period will there be, if the duration of every period is reduced by 5 minutes?

3.   A machine can fill 420 bottles of mineral water in 3 hours. How many bottles can be filled in 5 hours?

4.   In a model of a ship. the mast is 9 cm high, while the mast of the actual ship is 12 m high..

        If the length of the model ship is 21 cm, then how long is the actual ship?

5.   If kg of sugar contains 2.25 � 107 crystals. How many sugar crystals are there in 2 kg of sugar?