Mathalicious: New Twenty

How does life expectancy affect how you live your life?

With people settling down, starting a family, and even dying later and later, it’s becoming a common refrain that “30 is the new 20.” But what does this mean, and how might your life change if your life expectancy were different?

In this lesson, students use proportions to determine what life expectancy must have been in order for 30 to really be the new 20. They then extend their proportional reasoning to calculate the age at which certain life events would’ve happened in the past. Finally, they explore what might happen in the future, in a world where life expectancy hits 200 years.


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Math Topics
Algebra & Pre-Algebra, Ratios, Rates & Percents
Middle School
7th Grade

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