Goodness-of-Fit Test · Exercise 4

A teacher predicts that the distribution of grades on the final exam will be and they are recorded in.
$$\begin{array}{cc}\text{Grade}& \text{Proportion}\\ \text{A}& \text{0.25}\\ \text{B}& \text{0.30}\\ \text{C}& \text{0.35}\\ \text{D}& \text{0.10}\end{array}$$

The actual distribution for a class of 20 is in.
$$\begin{array}{cc}\text{Grade}& \text{Frequency}\\ \text{A}& \text{7}\\ \text{B}& \text{7}\\ \text{C}& \text{5}\\ \text{D}& \text{1}\end{array}$$

$df=$ ______

This exercise has fill-in blanks from its source book and no answer key.

OpenStax, Introductory Statistics 2e · §11.2 Goodness-of-Fit Test · Exercise 4