Quantitative Aptitude - Arithmetic Ability Questions

In what time will a 100 metre long train running with a speed of 50 km/hr cross a pillar?

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 average of 21 numbers is 12. The average of the first 11 numbers is 9 and the average of the last 11 numbers is 15. What is the value of the middle number?

If the volume of a cylinder is 3850 cubic cm and height is 25 cm, what is its radius? (Take π = 22/7)

If cosπ/4c - tanπ/4c = x, then x is

If xy+yz+zx = 1, then the value of (1+y2)(x+y)(y+z) ?

If a(x + y) = b(x - y) = 2ab, then the value of 2(x2 + y2)

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?