Quantitative Aptitude - Arithmetic Ability Questions

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

The brother is elder to his sister by 6 years. Seven years ago the product of their ages was 72. What is the age of the brother?

Each question contains Quantity I and Quantity II. Read the contents clearly and answer your questions accordingly.

Quantity I: Vipin can swim at 6 km/hr in still water. The river flows at 3 km/hr and it takes 8 hours more upstream then downstream for the same distance. How far is the place?

Quantity II: A man can row 25 km/hr in still water and the river is running at 15 km/hr. if the man takes 2 hr to row to a place and back, how far is the place?

Vijay can do a work in 8 hours. Vijay and Puneet together can do the same work in 6 hours. Puneet and Sachin together can do the same work in 4 hours. Sachin alone can complete the same work in how many hours?

A trader sells wire and gains 60% on the cost price. What will be the profit % on selling price?

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 √(1 - sin2A) = x, then the value of x is

If x + 1x = c + 1c, then the value of x =