Let:
N = Total people that took the test
A = Number of people who passed the test = 620
r = Percentage of the pass rate = 83% = 0.83
[tex]\begin{gathered} N\cdot r=A \\ so\colon \\ N=\frac{A}{r} \\ N=\frac{620}{0.83} \\ N=746.98\approx747 \end{gathered}[/tex]