Calculus need help please!

Question

The base of a solid in the region bounded by the graphs of y = e^-x y = 0, and x = 0, and x = 1. Cross sections of the solid perpendicular to the x-axis are semicircles. What is the volume, in cubic units, of the solid? (4 points)

Answer Choices:

Answer 1

This volume V = ∫₀¹π/2(e^-x/2)²dx = - 1/16πe^-2x₀¹ = 1/16π - 1/16πe^-2 = π/16(1 - 1/e²).

Right answer is 2nd from the top.