Quiz: Assign and Modify Variables

Now it's your turn to work with variables. The comments in this quiz (the lines that begin with #) have instructions for creating and modifying variables. After each comment write a line of code that implements the instruction.

Note that this code uses scientific notation to define large numbers. 4.445e8 is equal to 4.445 * 10 ** 8 which is equal to 444500000.0.

Start Quiz:

# The current volume of a water reservoir (in cubic metres)
reservoir_volume = 4.445e8
# The amount of rainfall from a storm (in cubic metres)
rainfall = 5e6

# decrease the rainfall variable by 10% to account for runoff

# add the rainfall variable to the reservoir_volume variable

# increase reservoir_volume by 5% to account for stormwater that flows
# into the reservoir in the days following the storm

# decrease reservoir_volume by 5% to account for evaporation

# subtract 2.5e5 cubic metres from reservoir_volume to account for water
# that's piped to arid regions.

# print the new value of the reservoir_volume variable

Quiz: Changing Variable Values

How does changing the value of a variable affect another variable that was defined in terms of it? Let's look at an example.

We're intentionally not providing a place to execute the code here, because we want to help you practice the important skill of walking through lines of code by hand.

Each line of code executes in order, one at a time, with control going from one line to the next.

>>> carrots = 24
>>> rabbits = 8
>>> crs_per_rab = carrots/rabbits

Now we add a new 4th line to this code, that assigns a new value to the rabbits variable:

>>> rabbits = 12