Quantitative Aptitude - Arithmetic Ability Questions

An angle in a semicircle is

The circumference of a circle is equal to the perimeter of an equilateral Δ. If the radius of the circle is 14 cm what is the length of the side of the equilateral Δ?

Two pipes P and Q can fill an empty tank in 25 hours and 20 hours respectively. Pipe R alone can empty the completely filled tank in 50 hours. Firstly both the pipes P and Q are opened and after 8 hours pipe R is also opened. What will be the total time (in hours) taken to completely fill the tank?

What is the value of ( 1/√3 + cot60) ?

If 3cos2x - 2sin2x = -0.75 and 0°⩽ x ⩽ 90°, then x = ?

15 small rods, each of length 23 2/7 m are joined to make a big rod. What then is the length of the big rod?

What is the circumference (in cm) of a circle whose area is 616 sq cm?

What is the curved surface area (in cm²) of a hemisphere of diameter 42 cm?