Final answer:
To calculate the cost of 7 packets of coffee each weighing 1.2kg, determine the cost per gram based on the given 8 packets of 200g each costing Rs 400. Then multiply the total grams of the 7 packets by the cost per gram to find the total cost of Rs 2100, which is not listed in the given options.
Step-by-step explanation:
The question asks to find the cost of 7 packets of coffee, each weighing 1.2kg, given that 8 packets of coffee weighing 200g each cost Rs 400. We start by determining the total weight of the 8 packets and then find the cost per gram. Next, we calculate the total weight of the 7 packets and then use the cost per gram to determine the total cost of these 7 packets.
First, we calculate the total weight of the 8 packets: 200g per packet × 8 packets = 1600g.
The cost of 1600g of coffee is Rs 400, so the cost per gram is Rs 400 / 1600g = Rs 0.25 per gram.
Now, we need to convert the weight of the 7 packets to grams: 1.2kg per packet × 1000g/kg = 1200g per packet, so for 7 packets: 1200g per packet × 7 = 8400g.
Finally, the cost of 8400g of coffee is: 8400g × Rs 0.25 per gram = Rs 2100.
However, none of the given options matches the correct cost of Rs 2100. Therefore, it seems there might be a typo or a mistake in the presented options or in the problem setup, as the expected answer is not listed.
In terms of proportion, if we were to assume that the cost directly varies with weight (which is typically the case), then we would consider this to be a case of direct proportion.