Quantitative Aptitude - Arithmetic Ability Questions

A merchant changed his trade discount from 25% to 15%. This would increase selling price by

X alone can do a piece of work in 12 days and Y alone can do the same work in 6 days. In how many days will both together complete the same work?

If tanθ = 43, then the value of 3sinθ+2cosθ3sinθ-2cosθ ?

If α and β are the roots of equation x2 – 2x + 4 = 0, then what is the equation whose roots are α3/β2 and β3/α2?

If the standard deviation of a population is 10, what would be the population variance?

A pentagonal prism has 15 edges. How many vertices does it have?

If x + (1/x) = √13, then what is the value of x5 – (1/x5)?

Two circles are having radii 9 cm and 12 cm. The distance between their centres is 15 cm. What is the length (in cm) of their common chord?