add chapter 3

ch3/01.cpp

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+# include <iostream>
+using namespace std;
+const int feet2inch = 12;
+
+int main(){
+	int height;
+	cout << "Enter Your Height (feet): ";
+	cin >> height;
+	int inch = height / feet2inch;
+	int feet = height % feet2inch;
+	cout << "Your Height is " << inch << " inch " << feet << " feet" << endl; 
+	return 0;
+}

ch3/02.cpp

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+# include <iostream>
+# include <cmath>
+using namespace std;
+int ic2ft = 12; // 1 inch = 12 feet
+double ft2m = 0.0254; // 1 feet = 0.0254 meter
+float kg2p = 2.2;
+double bmi (double a, double b);
+
+int main(){
+	double inch, feet;
+	double pound;
+	cout << "Enter Your Height (Inch feet): ";
+	cin >> inch >> feet;
+	double meter = (inch * ic2ft + feet) * ft2m;
+	cout << "Enter Your Weight (pound): ";
+	cin >> pound;
+	double kg = pound / kg2p; 
+	double c = bmi (kg, meter);
+	cout << "The BIM is " << c << endl;	
+	return 0;
+}
+
+double bmi (double a, double b){
+	double c = 1 / pow(b,2) * a;
+	return c;
+}

ch3/03.cpp

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+# include <iostream>
+# include <cmath>
+using namespace std;
+int conv = 60;
+
+int main(){
+	int degree, minute, second;
+	cout << "Enter a latitude in degrees, minutes and second" << endl;
+	cout << "First, enter the degrees: ";
+	cin >> degree;
+	cout << "Next, enter the minutes: ";
+	cin >> minute;
+	cout << "Finally, enter the seconds: ";
+	cin >> second;
+	float degree_f = degree + minute/float(conv) + second/float(pow(conv,2));
+	cout << degree << " degrees, " << minute <<  " minutes, " << second <<  " seconds = " << degree_f << " degrees" << endl ;
+	return 0;
+}

ch3/04.cpp

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+# include <iostream>
+# include <cmath>
+using namespace std;
+long convt = 60;
+long convd = 24;
+int main(){
+	long time_all;
+	cout << "Enter the number of seconds: ";
+	cin >> time_all;
+	int day, hour, minute, second;
+	day = time_all / pow(convt,2) / convd;
+	hour = (time_all - day * pow(convt,2) * convd)/ pow(convt,2);
+	minute = (time_all - day * pow(convt,2) * convd - hour * pow(convt,2)) / pow (convt,1);
+	second = time_all - day * pow(convt,2) * convd - hour * pow(convt,2) - minute * pow (convt,1);
+	cout  << time_all << " secods = "  << day << " days, " << hour << " hours, " << minute << " minutes, " << second << " seoncds\n";
+	return 0;
+}

ch3/05.cpp

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+# include <iostream>
+using namespace std;
+
+int main(){
+	long long wd_pop = 6898758899, us_pop = 310783781;
+	double rate = double(us_pop) / double(wd_pop);
+	cout << "There are " << wd_pop << " people in the world" << endl;
+	cout << "There are " << us_pop << " people in the US" << endl;
+	cout << "The population of the US is " <<  rate << "% of the world population" << endl;
+	return 0;
+}

ch3/06.cpp

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+# include <iostream>
+using namespace std;
+
+int main(){
+	double ga, mi;
+	cout << "The usage of oil (Gallon): ";
+	cin >> ga;
+	cout << "The miles you drive: ";
+	cin >> mi;
+	double mi_per_ga = mi / ga;
+	cout << "Every gallon, the driver can drive " << mi_per_ga << " mile(s)" << endl;
+	return 0;
+}

ch3/07.cpp

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+# include <iostream>
+using namespace std;
+double km2mile = 0.6214;
+double ga2l = 3.875;
+
+int main(){
+	double ga, mi, eu_rate;
+	cout << "The usage of oil (L) per 100 km: ";
+	cin >> eu_rate;
+	double us_rate =  km2mile * ga2l / eu_rate;
+	cout << "Every gallon, the driver can drive " << us_rate << " mile(s)" << endl;
+	return 0;
+}