Quantitative Aptitude - Arithmetic Ability Questions

In the following question, select the odd letter/letters from the given alternatives.

The price of a chair is Rs. 500. It has been sold at two succesive discounts of 10% each. What is its selling price?

Two pipes fill a tank when working individually in 25 and 40 hours, respectively while a third pipe can drain the filled tank in 16 hours. If all the three pipes are turned on at the same time when the tank is empty, how long will it take to fill the tank completely ?

If (a+1a)2=3,then the value of a6-1a6 will be

A chord of length 60 cm is at a distance of 16 cm from the centre of a circle. What is the radius (in cm) of the circle?

The two lines 4x+3y=0 and 7x+5y=0 will ______ in their graphical representation.

38% of 250 is equal to

If (1 + cosA)/(1 - cosA) = x, then x is