In the x- y plane, there are 4 points (0,0), (0,4), (5,4), and (5,0). If these 4 points makes a rectangle, what is the probability that x+y<4?  Choose the correct answer
A) 2/3 B) 2/5 C) 3/4 D) 3/7 E) 5/8
The line y=-x+4 intersects the rectangle and these three points of intersection (0,0), (0,4) and (4,0) form a triangle.   The points below the line y=-x+4 satisfy x+y&lt;4.   The area of this triangle is (1/2)(4)(4)=8   The area of the rectangle is 20.   P(x+y&lt;4) = 8/20 = 2/5   The answer is 2/5.
<result>B</result>
In the x- y plane, there are 4 points (0,0), (0,4), (5,4), and (5,0). If these 4 points makes a rectangle, what is the probability that x+y<4?