Quantitative Aptitude - Arithmetic Ability Questions

The HCF of 24, 60 and 90 is:

ΔDEF is right angled at E. If cosD = 8/17, then what is the value of secF ?

What will be the quotient when 2143 is divided by 38?

If a4 + 1 = [a2 /b2 ] (4b2 – b4 – 1), then what is the value of a4 + b4?

Two numbers are 35% and 40% lesser than a third number. By how much percent is the second number to be enhanced to make it equal to the first number?

A person goes from point N to P and comes back. His average speed for the whole journey is 60 km/hr. If his speed while going from N to P is 40 km/hr, then what will be the speed of the person (in km/hr) while coming back from P to N?

The line segment AB intersects the straight line CD at B; AB will be smallest when ∠ ABD (in degrees) is

If a - b = 3 and a2+b2=25, then the value of ab is