Trade payables turnover ratio = \(\frac{Net\ credit\ purchases}{Average\ trade\ payables}\) = \(\frac{1,00,000}{20,000}\) = 5 times
Average trade payables = \(\frac{Opening\ trade\ payables + Closing\ trade\ payables}{2}\)
= \(\frac{(20,000 + 4,000) + (10,000 + 6,000)}{2}\) = Rs.20,000
payment period (in days) = \(\frac{Number\ of\ days\ in\ a\ year}{Trade\ payables\ turnover\ ratio}\) = \(\frac{365}{5}\) = 73 days. 

Inventory turnover ratio = \(\frac{Cost\ of\ revenue\ from\ operations}{Average\ inventory}\) = \(\frac{1,20,000}{30,000}\) = 4 times
Cost of revenue from operations
= Opening inventory + Net Purchases + Direct expenses (carriage inwards) – Closing inventory
= 40,000 + 90,000 + 10,000 – 20,000
= Rs.1,20,000
Average inventory = \(\frac{Opening\ inventory + Closing\ inventory}{2}\)
= \(\frac{40,000 + 20,000}{2}\) = Rs.30,000
Inventory conversion period (in months) = \(\frac{Number\ of\ months\ in\ a\ year}{Inventory\ turnover\ ratio}\) = \(\frac{12}{4}\) = 3 months

Following are the limitations of ratio analysis:
(i) Accuracy of financial information : The accuracy of a ratio depends on the accuracy of information taken from financial statements.
(ii) Consistency in preparation of financial statements: Inter-firm comparisons with the help of ratio analysis will be meaningful only if the firms follow uniform accounting procedures consistently.
(iii) Non-availability of standards or norms: Ratios will be meaningful only if they are compared with accepted standards or norms. Only few financial ratios have universally recognised standards.
(iv) Change in price level : Ratio analysis may not reflect price level changes and current values as they are calculated based on historical data given in financial statements.

(i) Operating profit ratio gives the proportion of operating profit to revenue from operations.
(ii) Operating profit ratio is an indicator of operational efficiency of an organisation.
(iii) It may be computed as follows: Operating profit ratio
= \(\frac { Operating\ profit }{ Revenue\ from\ operations } \times 100\)
Alternatively, it is calculated as under.
Operating profit ratio = 100% - Operating cost ratio
Operating profit = Revenue from operations - Operating cost
(iv) A higher ratio indicates better profitability. Greater the operting ratio, higher is the margin available for paying non-operating expenses.

(i) Inventory turnover ratio = \(\frac{Cost\ of\ revenue\ from\ operations}{Average\ inventory}\) = \(\frac{6,00,000}{1,20,000}\) = 5 times
Average inventory = \(\frac{Opening\ inventory + Closing\ inventory}{2}\)
= \(\frac{1,40,000 + 1,00,000}{2}\)= \(\frac{2,40,000}{2}\)= Rs. 1,20,000
(ii) Trade receivables turnover ratio = \(\frac{Credit\ revenue\ from\ operations}{Average\ trade\ receivables}\)
= \(\frac{10,50,000}{70,000}\) = 15 times
Average trade receivables = \(\frac{Opening\ trade\ receivables + Closing\ trade\ receivables}{2}\)
= \(\frac{80,000 + 60,000}{2}\) =\(\frac{1,40,000}{2}\)= Rs.70,000
(iii) Creditors payables turnover ratio = \(\frac{Net\ credit purchases}{Average\ trade\ payables}\) = \(\frac{4,50,000}{45,000}\)= 10 times
Average trade payables = \(\frac{Opening\ trade\ payables + Closing\ trade\ payables}{2}\)
= \(\frac{40,000 + 50,000}{2}\) = \(\frac{90,000}{2}\) = Rs. 45,000
(iv) Fixed assets turnover ratio = \(\frac{Revenue\ from\ operations}{Average\ xed\ assets}\)= \(\frac{10,50,000}{5,25,000}\) = 2 times
Average fixed assets = \(\frac{Opening\ fixed\ assets + Closing\ fixed\ assets}{2}\)
= \(\frac{5,50,000 + 5,00,000}{2}\) = \(\frac{10,50,000}{2}\)= Rs. 5,25,000