Fourier package causes equation to not show up properly

Question

In the MWE below, I do not get the equation to show up properly. This is how it shows up:

when this is the equation:

E(T) = C_{1} + C_{2}f_{1}[p(t)] + C_{3}f_{2}[T(t)] + C_{4}f_{3}[p(t),T(t)] + v(t)

I did the updmap.exe and also ran the "REFRESH FNDB" in MiKTeX for Windows but still did not get the equation to show up properly. I am using the Fourier package because it is being used in the chapter title headings. Can the Fourier package work here in conjunction with the equations showing up correctely?

Here is my MWE:

\documentclass{book}
\usepackage{etoolbox,fancyhdr}
\usepackage[top=3cm,bottom=3cm,left=3.2cm,right=3.2cm,headsep=10pt,a4paper]{geometry}
\usepackage{graphicx, rotating, ltablex, dcolumn, booktabs}
\usepackage{siunitx} 
\usepackage{booktabs}
\usepackage{xcolor}
\definecolor{ocre}{RGB}{52,177,201}
\usepackage{amsmath,amsfonts,amssymb,amsthm}
\usepackage{microtype}
\usepackage[utf8]{inputenc} 
\usepackage[T1]{fontenc}
\usepackage{tikz}
\usepackage{calc}

\usepackage{fourier}
\usepackage{mathptmx}

\begin{document}

\chapter{Chapter 1}

\section{Problem 2.4}\index{Problem 2.4}

(Mendel, 1973, Exercise 1-17, pp. 46-47).  The efficiency of a jet engine may be viewed as a linear combination of functions of inlet pressure $p(t)$ and the operating temperature $T(t)$; i.e.,
\begin{equation*}
E(T) = C_{1} + C_{2}f_{1}[p(t)] + C_{3}f_{2}[T(t)] + C_{4}f_{3}[p(t),T(t)] + v(t)
\end{equation*}
where the structures of $f_{1}$, $f_{2}$, and $f_{3}$ are known a priori and $v(t)$ represents modeling error of known mean and variance.  From tests on the engine a table of values of $E(t)$, $p(t)$, and $T(t)$ is given at discrete values of $t$.  Explain how $C_{1}$, $C_{2}$, $C_{3}$, and $C_{4}$ are estimated from these data.

\end{document} 

Answer 1

You either want fourier (in order to get the document in Utopia) or mathptmx (so the font will be Times Roman). Not both: see Incompatibilities between fourier and other mathfont for another similar situation.

Loading both packages will result in a disaster, because fourier uses non standard math font encodings, which are set at \begin{document}, so many symbol commands will point to the wrong position in the font.

Other font packages with an accompanying math font may be loaded together and the last one prevails, but it's better having just one. The reverse order (first mathptmx, then fourier) is good, but the first package will do nothing, so it's better not to load it to begin with.

Instead of mathptmx you can consider

\usepackage{newtxtext,newtxmath}

because you have a richer supply of symbols (bold symbols, for instance).