python - 使用百分比分配和修改变量（计算）

Question

我是 Python 新手。我熟悉变量并为它们赋值。

但目前我陷入了以下计算。

# current volume of a water reservoir (in cubic meters)
reservoir_volume = 4.445e8

# amount of rainfall from a storm (in cubic meters)
rainfall = 5e6

# decrease the rainfall by 10% to account for runoff
rainfall*=(10/100)

# add the rainfall to the reservoir_volume
rainfall += reservoir_volume

# increase reservoir_volume by 5% to account for storm water
# that flows into the reservoir in the days following the storm
reservoir_volume *= (5/100)

# decrease reservoir_volume by 5% to account for evaporation
reservoir_volume *= (5/100)

# subtract 2.5e5 cubic meters from reservoir_volume       
# to account for water that's piped to arid regions
reservoir_volume -= (2.5e5)

# print the new value of the reservoir_volume variable
print(reservoir_volume)

你能提供一些见解什么是不正确的吗？

标签： pythonvariablespercentage

Answer 1

# The amount of rainfall from a storm (in cubic metres)
rainfall = 5e6

# decrease the rainfall variable by 10% to account for runoff
rainfall = rainfall*0.90

# add the rainfall variable to the reservoir_volume variable
reservoir_volume = reservoir_volume + rainfall


# increase reservoir_volume by 5% to account for stormwater that flows
# into the reservoir in the days following the storm
reservoir_volume = reservoir_volume*1.05

# decrease reservoir_volume by 5% to account for evaporation
reservoir_volume = reservoir_volume*0.95


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

# print the new value of the reservoir_volume variable
print(reservoir_volume)