In a contingency table a sample of 400 people is classified by gender and four hair colors (blond, brown, black, and red). How many degrees of freedom are there?
A.1
B.3
C.8
D.399
- · 有4位网友选择 D,占比40%
- · 有3位网友选择 A,占比30%
- · 有2位网友选择 B,占比20%
- · 有1位网友选择 C,占比10%