In order to find the volume of the figure, use the following formula:
V = l·w·h
l: length = 5 in
w: width = 1 in
h: height = 1.5 in
replace the previous values of the paramters into the formula for V:
V = (5 in)(1 in)(1.5 in)
V = 7.5 in³
Hence, the voluem of the given rectangular prism is 7.5 in³