By selling an article for Rs. 320, a man incurs a loss of 20%, what should be the selling price of an article to gain 30%?

A number increased by   $$22{1 \over 2}\%$$ gives 98 as result. The number is: 

A piece of land came to a person through three middlemen each gaining 20%. If the person purchased the land for Rs. 3,45,600 the original cost of the land was: 

The equidistant point from the vertices of a triangle is called its: 

A racing car going at an average speed of 108 km/ hr takes 15 minutes to complete a lap on a racing track. By how much should it increase its speed (in km/hr) to complete the lap in 12 minutes?

The average of the marks obtained in an examination by 8 students was 51 and by 9 other students was 68. The average marks of all 17 students was: 

A train travelling at the speed of 50 kmph leaves from a station. Another train travelling at speed of 60 kmph leaves the same station after 7 hours in the same direction. They will meet after what distance?