Short answer: P=0.25
Step One
Find the area of the shaded area
Area = L * W
L = 1.5 feeet
W = 1 foot
Area = 1.5 * 1 = 1.5 ft^2
Step Two
Find the total area
Total Area = L * W
L = 3 feet
W = 2
Area = 3 * 2 = 6 feet^2
Step Three
P = Shaded Area / Total Area
P = 1.5 / 6
P = 1/4
Discussion
This problem should make you a bit uncomfortable. I'm answering it exactly the way it is asked, but if you do hit the shaded area, does it count as a hit in the entire area as well? I would answer the way it is asked, but it is something to look out for in the future.