IMAT 2015 Q17 [Fence Rails]

A farmer wishes to fix fencing rails to posts which are already in place. The posts are shown in the diagram. The farmer has a supply of rails, each one 2.4 m long. One rail or part of a rail is to be fixed between each pair of posts. (He can cut the rails into smaller lengths.)

image

What is the smallest number of rails that he could use?

A. 5
B. 3
C. 4
D. 6
E. 7