correct answer is: c) ₹ 360

Explanation

To find the cost of 0.15 part of a bag of rice, we can use ‘Proportion Method’.
Let, the cost of 0.15 part of a bag of rice =\;₹\;‘x’
According to the question,
\large\frac{0.15}{0.75}=\frac{x}{1800}
\rightarrow\large\frac{15\times100}{75\times100}=\frac{x}{1800} _{[remove decimal]}
\rightarrow\large\frac{1}{5}=\frac{x}{1800}
\rightarrow5x=1800 _{[interchange]}
\rightarrow\ x=\large\frac{1800}{5}
\rightarrow\ x=360
\therefore The cost of 0.15 part of a bag of rice is ₹\;360 .
Ans: If the cost of 0.75 part of a bag of rice is ₹ 1800, then the cost of 0.15 part of it is ₹ 360.

There’s another way to pose this same question:
1. Determine the cost of purchasing 0.15 part of a bag of rice when the cost of 0.75 part is ₹1800.
2. Calculate the cost of 0.15 part of a bag of rice if the cost of 0.75 part is ₹1800.
3. Find out the price of 0.15 part of a bag of rice given that the cost of 0.75 part is ₹1800.
4. What is the cost of 0.15 part of a bag of rice if the cost of 0.75 part is ₹1800?