In an influenza epidemic, the number of cases diagnosed in a week were as follows:
| Day | Monday | Tuesday | Wednesday | Thursday | Friday | Saturday | Sunday |
| Number of Cases | 10 | 12 | 8 | 16 | 9 | 14 | 4 |
The 3-day moving averages are:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 10, 12, 11, 13, 9
Each 3-day moving average is the mean of three consecutive values, the window moving on by one day each time:
\( \displaystyle \frac{10 + 12 + 8}{3} = \frac{30}{3} = 10 \)
\( \displaystyle \frac{12 + 8 + 16}{3} = \frac{36}{3} = 12 \)
\( \displaystyle \frac{8 + 16 + 9}{3} = \frac{33}{3} = 11 \)
\( \displaystyle \frac{16 + 9 + 14}{3} = \frac{39}{3} = 13 \)
\( \displaystyle \frac{9 + 14 + 4}{3} = \frac{27}{3} = 9 \)
So the moving averages are 10, 12, 11, 13, 9.