Moving average

Sir in bpp text, there’s an example i came across 11.3

Example: forecasting by rough approximation

The sales in $’000 of swimwear by a large department store for each period of three months are as follows.

Quarter 20X4. 20X5. 20X6. 20X7
$000. $000. $000. $000
First. 8. 20. 40
Second. 30. 50. 62
Third. 60 80. 92
Fourth. 24. 20. 40

Required

Using an additive model, find centred moving avg trend

And here sir they are first figuring out centred moving total of 4th quarter moving total though we are supposed to find avg of moving total and then find the centred moving avg, could you please explain me this, I just watched your lecture again on this topic but i have this confusion

So i will show in short what they’re doing

20X4 quarter we got 24 just of 4th quarter added with the rest quarters of 20X5 gives us total moving total 122, then they find centred moving total by adding 122 and 118 of 4th quarter of 20X5 which gives us 120 and then dividing 120 by 4 which they’ve shown as moving avg of 30

So what I don’t get is moving average is of moving total and then we find 2nd moving avg

And I’ve done it like this

First i find the 4 quarter moving total which is 122 and divide it by 4 gives me 30.5 and then 118 by 4 is 29.5 so both moving avg i find the centred moving avg which results in same =30, could you please tell me which is correct also would we be asked in exam to present centred moving total as well?