In [4]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
T1=1.5; #R time for empty hall(s)
T2=1; #R time with curtain cloth(s)
A=20; #area of absorber(sq.m)
V=10*8*6; #volume of hall(cu.m)
#Calculation
a=((0.161*V)/(2*A))*((1/T2)-(1/T1)); #absorption coefficient
#Result
print "absorption coefficient is",round(a,2),"Sabines"
print "answer given in the book varies due to rounding off errors"
```

In [8]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
V=20*15*10; #volume of hall(cu.m)
T1=3.5; #reverberation time(s)
l=20;
b=15;
h=10; #dimensions of hall
am=0.5; #absorption coefficient
T2=2.5; #reverberation time after cloth use(s)
#Calculation
A=(0.161*V)/T1;
S=2*((l*b)+(b*h)+(h*l)); #surface area(sq.m)
sigma_a=A/S; #average absorption coefficient of hall(o.w.u)
S1=(((0.161*V)/(am-sigma_a))*((1/T2)-(1/T1))); #area of wall covered by curtain cloth(sq.m)
#Result
print "average absorption coefficient of hall is",round(sigma_a,3),"o.w.u"
print "area of wall covered by curtain cloth is",round(S1,3),"sq.m"
print "answer for area covered S1 varies due to rounding off errors"
```

In [12]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
V=1450; #volume of hall(cu.m)
A1=112*0.03; #absorption due to plastered wall
A2=130*0.06; #absorption due to wooden floor
A3=170*0.04; #absorption due to plastered ceiling
A4=20*0.06; #absorption due to wooden door
A5=100*1; #absorption due to cushioned chairs
#Calculation
sigma_as=A1+A2+A3+A4+A5; #total absorption in empty hall
T1=(0.161*V)/sigma_as; #reverberation time case-1(s)
T2=(0.161*V)/(sigma_as+(60*4.7)); #persons=60,A=4.7 case-2
T3=(0.161*V)/(sigma_as+(100*4.7)); #seat cushioned=100 case-3
#Result
print "reverberation time for case-1 is",round(T1,3),"sec"
print "reverberation time for case-2 is",round(T2,3),"sec"
print "reverberation time for case-3 is",round(T3,3),"sec"
print "answer for T3 given in the book is wrong"
```