$\quad \lambda=10 \;cl/h, \quad t=100 \;h \quad \Rightarrow \quad y=\lambda \cdot t=1000 \; cl, \quad E[A]=6 \; min$
$\quad \lambda=12 \;cl/h, \quad \mu=4 \;cl/h \quad \Rightarrow \quad L={\lambda \over \mu} =3$
$ \quad \lambda = 10 \; cl/h \quad \mu = 4 \; cl/h \quad c = 3 \quad \quad \Rightarrow \quad \rho = {\lambda \over {c \mu}} = {5 \over 6} < 1 $
lb = 10 # 10 cl/h
mu = 4 # 60*1/15 cl/h
c = 3
rho = lb / (c*mu)
print(lb,mu,c,rho)
$ \quad \pi_0 = {1 \over {\sum _{j=0} ^{c-1} {{(c \rho)^j} \over {j!}} + {{(c \rho)^c} \over {c!(1-\rho)}}}} = 0.0449 \quad L_q = {{(c\rho)^c \rho} \over {c!(1-\rho)^2}} \pi _0 = 3.51 \quad W_q = {{L_q} \over {\lambda}} = 21 \; min $
a = b = 1
for j in range(1,c):
b*=(c*rho)/j
a+=b
b*=((c*rho)/c)/(1-rho)
a+=b
pi0=1/a
print(pi0)
Lq=b*(rho/(1-rho))*pi0
Wq=60*Lq/lb # em minutos
print(Lq,Wq)