The histogram above shows the ages of victims of a pollution. How many people were involved in the pollution?
A.
20
B.
21
C.
15
D.
18
Correct answer is A
\(\begin{array}{c|c} \text{Age in years} & 10 & 20 & 30 & 40 & 50 \\\hline \text{frequency} & 3 & 4 & 5 & 6 & 2\end{array}\)
\(\sum f \) = number of people involved in the pollution
\(\sum f\) = 3 + 4 + 5 + 6 + 2 = 20