Quantitative Aptitude - Arithmetic Ability Questions

In the figure, B and C are the centres of the two circles. ADE is the common tangent to the two circles. If the ratio of the radius of both the circles is 3:5 and AC= 40, then what is the value of DE?

The standard deviation of the set {10, 11, 9, 11, 9} is

If a+b=2c then the value of aa-c+cb-c is equal to (where a≠b≠c)

A and B have to type a book together containing 120 pages. A takes 9 hrs to type 36 pages and B takes 5 hrs to type 40 pages. A typed first 60 pages alone and the last 60 pages were typed by A and B together. How much time (in hours) will be taken to type the complete book?

Mansukh can do a piece of work in 10 hours. If he is joined by Jayanti who is 50% more efficient, in what time will they together finish the work?

Complete the analogy 3 : 11 :: 7 : ___

A shopkeeper allows a discount of 20% to his customers and still gains 25%. Find the Marked price of an article which costs Rs.600 to the shopkeeper.

If √3 = 1.732, then the value of 9+233?