Python - Que tengo malo en este programa?

import math

cont = 0

prom = 0

for l in range (3713,4725):

    if l%7==0:

        L = 5*l

        area = (L*L/2)

        prom += area

        cont += 1

promedio = prom / cont

cos = math.cos(promedio)

cos1 = (cos)**1/3

print (round(cos1,6))

import math

cont = 0

area = 0

for l in range (3713,4725):

    if l%7==0:

        L = 5*l

        area += ((math.sqrt(3)/4)*L**2)**(1/3.0)

        cont += 1

promedio = area/cont

cos = math.cos(promedio)

print (round(cos,6))

import math

areas = []

for l in range (3713,4725):

    if l%7==0:

        L = 5*l

        areas.append(((math.sqrt(3)/4)*L**2)**(1/3.0))

promedio = sum(areas)/len(areas)

cos = math.cos(promedio)

print (round(cos,6))