A person travels 600 km by train at 80 km/hr 800 km by ship at 400 km/ hr and 100 km by car at 50 km/hr. What is the average speed for the entire distance? 

If 3 ^(X-Y)=27 and 3 ^(X+Y)=243, then X is equal to:

A pipe can fill a tank in 72 minutes. But there is a leak in the bottom of the tank due to which the tank is filled in 18 minutes more. Find in how many hours the leak can empty a full tank ?

$$ {109.07\sqrt{?}}-{61\over 21.02} ×?=47.96\sqrt{?}$$

Four bells ring at the intervals of 5, 6, 8, and 9 seconds. All the bells ring simultaneously at the same time. They will again ring simultaneously after: 

In two types of brass ratio of copper and zinc are 8: 3 and 15: 7 respectively. The ratio in which these two types of brass should be mixed, so that the ratio of copper and zinc in this new type of brass become 5: 2 is 

A field roller, in the shape of a cylinder, has a diameter of 1 meter and length of $$ {1}{1\over4}$$ meter. If the speed at which the roller rolls is 14 revolutions per minute, then the maximum area ( in m²) that it can roll in 1 hour is:

A man starts from his house and travelling at 30 km/h, he reaches his office late by 10 minute, and travelling at 24 km/h, he reaches his office late by 18 minutes. The distance (in km) from his house to his office is: