Answer
In terms of consecutive classes, the most extreme change is between the sixth class and seventh class or between the seventh class and the eighth class. The least extreme change is between the first class and second class.
If we are comparing non-consecutive classes, the most extreme change is between the fifth and tenth classes. The least extreme change is between the fourth and sixth classes.
Work Step by Step
First class (0-9) population: $\approx42$ millions.
Second class (10-19) population: $\approx41$ millions.
Third class (20-29) population: $\approx43$ millions.
Fourth class (30-39) population: $\approx40$ millions.
Fifth class (40-49) population: $\approx44$ millions.
Sixth class (50-59) population: $\approx40$ millions.
Seventh class (60-69) population: $\approx28$ millions.
Eighth class (70-79) population: $\approx16$ millions.
Nineth class (80-89) population: $\approx10$ millions.
Tenth class (90-99) population: $\approx2$ millions.
$Sixth~class~population-seventh~class~population=40-28=12$ millions.
$Seventh~class~population-eighth~class~population=28-16=12$ millions.
$First~class~population-second~class~population=42-41=1$ million.
