Answer:
H(s) = Â 10 / [ 1 + s / (200*10^3Ï€ ) ]^2
Explanation:
Characteristics of the high pass filter
Cutoff frequency = 100 kHz
stopband attenuation rate = 40 dB/decade
nominal passband gain = 20dB Â = 20logK = 20
Formula for H(s) satisfying the requirements above
given that the stopband attenuation = 40 dB/decade the formula for H(s) that will satisfy the requirements is a second order filter
H(s) = K / ( 1 + s/Wo ) ^2 Â ----- ( 1 )
Wo = 2πf = 2π ( 100 * 10^3 ) =  200 * 10^3 π
 K = 10
back to equation ( 1 )
H(s) = Â 10 / [ 1 + s / (200*10^3Ï€ ) ]^2