Quantitative Aptitude - Arithmetic Ability Questions

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

What is the simplified value of (sec4 A – tan2 A) – (tan4 A + sec2 A)?

If 1/√(1 + cot2A) = x, then value of x is

A ladder 13 m long reaches a window which is 12 m above the ground on side of a street. Keeping its foot at the same point, the ladder is turned to the other side of the street to each a window 5m high, then the width of the street is :

Two valves P and B can fill a sump in 37.5 minutes and 45 minutes respectively. Both valves are opened. The sump will be filled in just 30 minutes, if valve B is turned off after

In triangle ABC, ∠ABC = 15 deg. D is a point on BC such that AD = BD. What is the measure of ∠ADC (in degrees)?

If an equilateral triangle has side 12 cm, then what is the difference (in cm) between the circumradius and inradius?

In the following question, select the related number from the given alternatives.
 
47 : 57 : : 93 : ?