I need help trying to understand how they solved this equation. Just a little confused.

Answer:
0.495
Explanation:
Given the expression:
[tex]0.55-1.645\sqrt[]{\frac{0.55(1-0.55)}{220}}[/tex]Begin by simplifying the expression under the radical (square root) sign.
[tex]\begin{gathered} =0.55-1.645\sqrt[]{\frac{0.55(0.45)}{220}} \\ =0.55-1.645\sqrt[]{\frac{0.2475}{220}} \end{gathered}[/tex]Using a calculator, we evaluate the radical:
[tex]\begin{gathered} =0.55-1.645\sqrt[]{0.001125} \\ =0.494825 \\ \approx0.495\text{ (to 3 decimal places)} \end{gathered}[/tex]