The number of wedding cards, in thousands, distributed in a certain city on each day for a week is given as follows:-
21, 35, 19, 27, 32, 22, 12.
The three days moving averages will be:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 25, 27, 26, 27, 22
A three-day moving average is the average of each set of three consecutive days, moving one day at a time.
\( \displaystyle \frac{21+35+19}{3}=\frac{75}{3}=25 \)
\( \displaystyle \frac{35+19+27}{3}=\frac{81}{3}=27 \)
\( \displaystyle \frac{19+27+32}{3}=\frac{78}{3}=26 \)
\( \displaystyle \frac{27+32+22}{3}=\frac{81}{3}=27 \)
\( \displaystyle \frac{32+22+12}{3}=\frac{66}{3}=22 \)
So the three-day moving averages are 25, 27, 26, 27, 22.
Shortcut: Once the first total is known, each next total = previous total − the value dropped + the value added: 75 − 21 + 27 = 81, 81 − 35 + 32 = 78, 78 − 19 + 22 = 81, 81 − 27 + 12 = 66.