For the given five values: 18, 24, 12, 21, 30, the three-year moving averages are
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 18, 19, 21
Each three-year moving average is the mean of three consecutive values, starting one place later each time.
\( \displaystyle \frac{18+24+12}{3}=\frac{54}{3}=18 \)
\( \displaystyle \frac{24+12+21}{3}=\frac{57}{3}=19 \)
\( \displaystyle \frac{12+21+30}{3}=\frac{63}{3}=21 \)
So the moving averages are 18, 19, 21.