Two wave of intensities I and 4I superimpose,then the maximum and minimum intensities are..

9I and I

How..

If waves have intensity 4I and I
Let I =a^2 where a is amplitude of wave
I1=4a^2=(2a)^2
I2=a^2
Hence waves have amplitude of 2a and a
Imax=(2a+a)^2 = (3a)^2 = 9 a^2 = 9I
Imin = (2a-a)^2 = (a)^2 = I

Thank you...