A researcher for the EPA measured the amount of arsenic in the water near a sewage treatment plant. Over 12 days, he took
n
=
40
\displaystyle {n}={40}
n
=
40
measurements (in ppb). His sample data is summarized in the frequency distribution polygon shown below.
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How many measurements taken in this time frame were less than
50
\displaystyle {50}
50
ppb?
ans =
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