f(x) = 1/2 (3)^x
f(0) = 1/2 (3) ^ 0
f(0) = 1/2 x 0
f(0) = 0
0 to 1.5 is 1.5
f(1) = 1/2 (3) ^ 1
f(1) = 1/2 x 3
f(1) = 1.5
1.5 to 4.5 is 3
f(2) = 1/2 (3) ^ 2
f(2) = 1/2 x 9
f(2) = 4.5
4.5 to 13.5 is 9
f(3) = 1/2 (3) ^ 3
f(3) = 1/2 x 27
f(3) = 13.5
13.5 to 40.5 is 27
f(4) = 1/2 (3) ^ 4
f(4) = 1/2 x 81
f(4) = 40.5
40.5 to 121.5 is 81
f(5) = 1/2 (3) ^ 5
f(5) = 1/2 x 243
f(5) = 121.5
If you see what 3 ^ x is that is how much you add to your answer!!!
Hope this helped!!!!