₹ 180 contained in a box consists of one rupee, 50 paise and 25 paise coins in the ratio 2 : 3 : 4 . What is the number of 50 paise coins?

Everybody in a room shakes hands with everybody else. The total number of hand-shakes is 55. The total number of persons in the room is:

A 300-meter-long train moving with an average speed of 126 km/hr. crosses a platform in 24 seconds. A man crosses the same the same platforms in 5 minutes. What is the speed of man in meter/second?

QA and PB are perpendicular to AB in the given figure. If AO = 10 cm, BO = 6cm, BP = 9 cm, then the length of AQ is__

Mr. Duggal invested Rs. 20, 000 with rate of interest at 20 p.c.p.a. The interest was compounded half yearly for first year and in the next year it was compounded yearly. What will be the total interest earned at the end of two years? 

At what time between 5.30 and 6 will the hands of a clock be at right angles?

What value will come in the place of question mark in the following number series?
5 9 36 208 1398 ? 

A square has a perimeter equal to 24 units. If the length of each side of the square is reduced by 2 units, then find the area( in sq units) of the square.