Solutions¶

So you think you know your variables?

In [9]:

mallard_mass = 12;
earth_mass = 5.972e24;
mallard_population_2017 = 4.73e6;
mallard_population_2016 = 4.84e6;
pop_change = mallard_population_2017 - mallard_population_2016;
fprintf('Mallard pop. in 2017 was estimated to be %.2e \n', mallard_population_2017)
fprintf('Mallard pop. in 2016 was estimated to be %.0f, meaning there was an estimated change of %d mallards \n', mallard_population_2016, pop_change)
fprintf('In 2017, the mass of the global population of mallard ducks was %.2e percent of the mass of the Earth \n', mallard_mass*mallard_population_2017/earth_mass)
fprintf('In 2017, the mass of the global population of mallard ducks was %.2f percent of the mass of the Earth \n', mallard_mass*mallard_population_2017/earth_mass)

Mallard pop. in 2017 was estimated to be 4.73e+06 
Mallard pop. in 2016 was estimated to be 4840000, meaning there was an estimated change of -110000 mallards 
In 2017, the mass of the global population of mallard ducks was 9.50e-18 percent of the mass of the Earth 
In 2017, the mass of the global population of mallard ducks was 0.00 percent of the mass of the Earth

Notice how when dealing with large numbers, you should be careful when you print in float or scientific format - the final two print statements being an example!

mallard_mass = 12;
earth_mass = 5.972e24;
mallard_population_2017 = 4.73e6;
mallard_population_2016 = 4.84e6;
pop_change = mallard_population_2017 - mallard_population_2016;
fprintf('Mallard pop. in 2017 was estimated to be %.2e \n', mallard_population_2017)
fprintf('Mallard pop. in 2016 was estimated to be %.0f, meaning there was an estimated change of %d mallards \n', mallard_population_2016, pop_change)
fprintf('In 2017, the mass of the global population of mallard ducks was %.2e percent of the mass of the Earth \n', mallard_mass*mallard_population_2017/earth_mass)
fprintf('In 2017, the mass of the global population of mallard ducks was %.2f percent of the mass of the Earth \n', mallard_mass*mallard_population_2017/earth_mass)

mallard_mass = 12;
earth_mass = 5.972e24;
mallard_population_2017 = 4.73e6;
mallard_population_2016 = 4.84e6;
pop_change = mallard_population_2017 - mallard_population_2016;
fprintf('Mallard pop. in 2017 was estimated to be %.2e \n', mallard_population_2017)
fprintf('Mallard pop. in 2016 was estimated to be %.0f, meaning there was an estimated change of %d mallards \n', mallard_population_2016, pop_change)
fprintf('In 2017, the mass of the global population of mallard ducks was %.2e percent of the mass of the Earth \n', mallard_mass*mallard_population_2017/earth_mass)
fprintf('In 2017, the mass of the global population of mallard ducks was %.2f percent of the mass of the Earth \n', mallard_mass*mallard_population_2017/earth_mass)

Mallard pop. in 2017 was estimated to be 4.73e+06 
Mallard pop. in 2016 was estimated to be 4840000, meaning there was an estimated change of -110000 mallards 
In 2017, the mass of the global population of mallard ducks was 9.50e-18 percent of the mass of the Earth 
In 2017, the mass of the global population of mallard ducks was 0.00 percent of the mass of the Earth

Notice how when dealing with large numbers, you should be careful when you print in float or scientific format - the final two print statements being an example!