Diffentiate the function F(x)=(1/2x)^5

My answer is 5/2x^4. The book says 5/32x^4. what am I doing wrong?

realize that the 1/2 is inside the bracket , thus also raised to the 5th.

rewrite it as
f(x) = (1/32)x^5 then
f '(x) = (5/32)x^4