Quantitative Aptitude - Arithmetic Ability Questions

A solid sphere of diameter 17.5 cm is cut into two equal halves. What will be the increase (in cm2) in the total surface area?

3cosA is equal to

If 9x - 6(3 - x) = 12, then the value of x is

A number exceeds its 1/6 by 30. What is the number?

What are the co-ordinates of the centroid of a triangle, whose vertices are A(-2,5), B(3,-2) and C(5,3)?

If a perfect square, not divisible by 6, be divided by 6, the remainder will be

Working together, pipes A and B can fill an empty tank in 10 hours. They worked together for 4 hours and then B stopped and A continued filling the tank till it was full. It took a total of 13 hours to fill the tank. How long would it take A to fill the empty tank alone?

ABCD is a quadrilateral with AB = 9 cm, BC = 40 cm, CD = 28 cm, DA = 15 cm and angle ABC is a right –angel. 
What is the area of triangle ADC?