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Question 34 of 41
Q.

Find the trend using four yearly moving averages for the following data showing yearly sales (in lakh ₹) of a shop :

Year2015201620172018201920202021202220232024
Sales (lakh ₹)53764891089
Gujarat GsebGujarat Board (GSEB) HSC Commerce Board 2025Subjective· 5mImportance★★★★★
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4-yearly moving averages are centred (2-item average) to give the trend: 2017 → 5.125, 2018 → 5.625, 2019 → 6.5, 2020 → 7.25, 2021 → 8.25, 2022 → 8.875.

GSEB Class-12 Statistics, Time Series (moving average method, even period):

For a 4-yearly moving average the period is even, so the moving averages fall between years and must be centred by taking a further 2-item moving average.

Step 1 — 4-yearly moving totals and averages:

YearSales4-yearly moving total4-yearly moving average
20155
20163
5+3+7+6=215+3+7+6 = 2121/4=5.2521/4 = 5.25
20177
3+7+6+4=203+7+6+4 = 2020/4=5.0020/4 = 5.00
20186
7+6+4+8=257+6+4+8 = 2525/4=6.2525/4 = 6.25
20194
6+4+8+9=276+4+8+9 = 2727/4=6.7527/4 = 6.75
20208
4+8+9+10=314+8+9+10 = 3131/4=7.7531/4 = 7.75
20219
8+9+10+8=358+9+10+8 = 3535/4=8.7535/4 = 8.75
202210
9+10+8+9=369+10+8+9 = 3636/4=9.0036/4 = 9.00
20238
20249
…

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