The angle of elevation of ladder leaning against a house is 60° and the foot of the ladder is 6.5 meters from the house. The length of the ladder is 

If $$ {\sqrt{3}\ CosA=SinA}$$ then what is the value of Cot A?

5 men can do a piece of work in 6 days while 10 women can do it in 5 days. In how many days can 5 women and 3 men do it? 

A completes $$ {7\over 10}$$ of work in 15 days, then he completes the remaining work with the help of B in 4 days. The time required for A and B together to complete the entire work is

The speed of the motorboat in still water is 45 kmph. If the motorboat travels 80 km along the stream in 1 hour 20 minutes, then the time taken by it to cover the same distance against the stream will be: 

The present ages of two persons are 36 and 50 years respectively. If after n years the ratio of their age will be 3 : 4, then the value of n is 

Direction : What should come in place of the question (?) in the following question.

8424÷ 135 ×6=?

A 275 m long train crosses a platform of equal length in 33 s. What is the speed of the train in km/h?