Quantitative Aptitude - Arithmetic Ability Questions

If a - b = -7 and a2+ b2= 85, then find ab.

If 1/√(cosec2A - 1) = x, then value of x is

The distance between the centres of two circles is 61 cm and their radii are 35 cm and 24 cm. What is the length (in cm) of the direct common tangent to the circles?

A boat covers 143 km upstream in 13 hours and the same distance downstream in 11 hours. What is the speed (in km/hr) of the boat in still water?

A square is inscribed in a quarter circle in such a way that two of its adjacent vertices on the radius are equidistant from the centre and other two vertices lie on the circumference. If the side of square is √(5/2) cm, then what is the radius (in cm) of the circle?

A right circular solid cylinder has radius of base 7 cm and height is 28 cm. It is melted to form a cuboid such that the ratio of its side is 2 : 3 : 6. What is the total surface area (in cm2) cuboid?

The percentage change of a number when it is first decreased by 10% and then increased by 10% is

If 15 persons can do a job in 30 days, then 30 persons with twice the efficiency can do the same job in how many days?