The text for the averageFloats function is bold on page 254, but nothing seems to have changed between the version on page 253 and 254. The fact that #include <stdlib.h> isn’t needed does change but is a bit difficult to notice.
Each time the code is printed in the book there is a change. When the <stdlib.h> is omitted at the bottom of that code we change how we declare the float array from:
Unless you’re referring to a different bit of code.
(The page numbers are different on my book than yours due to the device I am reading it on I believe)