The ratio of maximum and minimum intensities in an interference pattern is 36:1. What is the ratio of the amplitudes of the two interfering waves ?

Given : 

$\begin{array}{l}\frac{I_{\max }}{I_{\min }}=\frac{36}{1}\\ \frac{A_1}{A_2}=?\\ Solution:-\frac{I_{\max }}{I_{\min }}=\frac{{(A_1+A_2)}^2}{{(A_1-A_2)}^2}=\frac{36}{1}\\ \therefore \frac{A_1+A_2}{A_1-A_2}=\frac{6}{1}\\ 1(A_1+A_2)=6(A_1-A_2)\\ 7A_2=5A_1\\ \therefore \frac{A_1}{A_2}=\frac{7}{5}\\ A_1:A_2::7:5\end{array}$