Question

The cost of \[27\] kg of iron is Rs \[1080\] what will be the cost of \[120\] kg of iron of the same quality?

Answer 1

Hint: In order to determine the cost of \[120\] kg of iron. To find the cost of \[120\] kg iron, we must know the cost of \[1\] kg. We already know the total cost of \[27\] kg is Rs \[1080\]. By solving this we will get the cost of \[1\] kg. Then we can easily find the cost of \[120\] kg by multiplying it with the cost of \[1\] kg.

Complete step by step solution:
In this problem,
We know that: \[27\] kg of iron is Rs \[1080\]. i.e., \[27{\text{kg}} = 1080\]
We have to find out the cost of \[1\] kg just divide the total cost by the total quantity purchased to get the cost of \[1\] kg.
Cost of \[1\] kg \[ = \dfrac{{{\text{total cost}}}}{{{\text{total quantity purchased}}}}\] .
Cost of \[1\] kg \[ = \dfrac{{1080}}{{27}}\] .
Cost of \[1\] kg \[ = 40\].
Therefore, the cost of \[1\]kg iron \[ = \]Rs \[40\] .
Now,
To find the cost of \[n\] kg just multiply the total kg by the cost of \[1\] kg.
Cost of \[120\] kg \[ = {\text{total kg}} \times {\text{cost of }}1{\text{ kg}}\] .
Cost of \[120\] kg \[ = 120 \times 40\] .
Cost of \[120\] kg \[ = \] Rs \[4800\] .
Hence, the cost of \[120\] kg of iron is Rs \[4800\].
So, the correct answer is “Rs \[4800\]”.

Note: To know the cost per kg or quantity “divide the total cost by the number of kg or quantity to determine the cost of each kg or quantity”.
To know the cost of \[n\] kg or quantity “multiply the total kg or quantity by the cost of \[1\] kg or quantity”.
Example: Price of \[4\] soap is Rs \[44\].Then what is the cost of \[1\] soap?
To find this we can simply divide the total cost \[44\] by the quantity \[4\], i.e., \[\dfrac{{44}}{4} = 11\].
Therefore the cost of \[1\] soap is Rs \[11\].