Here is the root locus for a simple control system.  The block diagram is shown first, and the root locus follows below.

From the root locus, you should be able to determine the following.

• The transfer function for the system being controlled.  The transfer function can be formed just by knowing the poles and zeroes which are shown on the root locus plot.
• Determine an adjusted system that has a DC gain of 1.0
• Using your adjusted system as G(s), determine the gain, K, which will produce poles at -2.5 +/- j 2.5.