Authors:
Y Daniel Lang
Chapter:
To Computers Programs And Python
Exercise:
Programming Excercises
Question:11 | ISBN:978013274719 | Edition: 6
Question
(Population projection) The US Census Bureau projects population based on the following assumptions:
One birth every 7 seconds
One death every 13 seconds
One new immigrant every 45 seconds
Write a program to display the population for each of the next five years. Assume the current population is 312032486 and one year has 365 days. Hint: in Python, you can use integer division operator // to perform division. The result is an integer. For
example, 5 // 4 is 1 (not 1.25) and 10 // 4 is 2 (not 2.5).
Answer
Python code:
print("current population: 312032486");
currentpopulation = 312032486;
#add one birth every 7 seconds; subtract one death every 13 seconds; add one immigrant every 45 seconds.
#365 days = 1 year | 1 day = 24 hours | 1 hour = 60 minutes | 1 minute = 60 seconds
#7 seconds = 1 birth | 13 seconds = 1 death | 45 seconds = 1 immigrant
#365days * 24hours * 60minutes * 60seconds = 31536000 seconds
numberOfSecondsInYear = 365 * 24 *60 * 60;
#After 1 year, number of births (7 seconds = 1 birth | plus)
birthsPerYear = numberOfSecondsInYear / 7;
print("brithsPerYear: ", int(birthsPerYear));
#After 1 year, number of deaths (13 seconds = 1 death | minus)
deathsPerYear = numberOfSecondsInYear / 13;
print("deathsPerYear: ", int(deathsPerYear));
#After 1 year, number of immigrants (45 seconds = 1 immigrant | plus)
immigrantsPerYear = numberOfSecondsInYear / 45;
print("immigrantsPerYear: ", int(immigrantsPerYear));
#Rate per year
ratePerYear = birthsPerYear - deathsPerYear + immigrantsPerYear;
print("ratePerYear: ", int(ratePerYear));
print("population after first year end :", int((currentpopulation + (1 * ratePerYear))));
print("population after second year end :",int((currentpopulation + (2 * ratePerYear))));
print("population after third year end :", int((currentpopulation + (3 * ratePerYear))));
print("population after fourth year end :",int((currentpopulation + (4 * ratePerYear))));
print("population after five year end :", int((currentpopulation + (5 * ratePerYear))));
Output:
Python 3.2.1 (default, Jul 10 2011, 21:51:15) [MSC v.1500 32 bit (Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> ================================ RESTART ================================
>>>
current population: 312032486
brithsPerYear: 4505142
deathsPerYear: 2425846
immigrantsPerYear: 700800
ratePerYear: 2780096
population after first year end : 314812582
population after second year end : 317592679
population after third year end : 320372776
population after fourth year end : 323152872
population after five year end : 325932969