Answer
About $80,000$ volunteers volunteered in environmental organizations.
Work Step by Step
The bar for 16 to 19 years olds represents 4 million volunteers.
Find $2\%$ of 4 million to obtain:
$=4,000,000 \times 2\%
\\=4,000,000 \times 0.02
\\=80,000$
Thus, about $80,000$ of the 16 to 19-year-old volunteers volunteered in environmental organizations.
