EIU Challenge of the Week

A fair die is rolled up to three times. At the end of each roll, you have the option to roll again or take the number showing in dollars. Wh...

Two people decide to meet for lunch between 12:00 and 1:00, but they don't set a fixed time. They randomly select a time independent of...

Can the sum of the reciprocals of a finite number of distinct positive integers be equal to 2009/2010? If yes, show such integers and if no...

Four race car drivers participate in a race on a loop track. All four are going at a constant speed. Assume that they make a flying start. ...

Two carts, A and B, are connected by a rope 28 ft long that passes over a pulley P (see the figure). The point Q lies 12 ft directly below P...

Is it possible to put 12 positive integers along a circle so that the ratio of any two neighboring integers is a prime number? (We take the ...

The integer lattice points are the points in the plane that have integer coordinates. Consider all squares in the plane with corners that ar...