Question

If the cost of 93m of a certain kind of plastic sheet is Rs.1395, then what would it cost to buy 105m of such plastic sheet?

Answer 1

Hint: Unitary method is the technique to first find the cost of a single unit and then find the cost of the required number of units. This method is also useful to find the cost of a single unit of a product from multiple numbers of units. Unitary generally means unit or units. The unitary method is also used to find the 100% of an amount; it means to say if the cost of some amount is given, then this method will be used to find the cost of the full amount. The unitary method is given as: \[P = \dfrac{a}{b} \times c\] where, ‘a’ is the cost of the product, ‘b’ is the units of the given product, ‘c’ is the units of the product whose cost is to be found, and ‘P’ is the cost of the required number of the product.
In this question cost is given for 93 meters of plastic, so first find the cost of 1 meter of that plastic and then find the cost of the required amount of plastic.

Complete step by step solution: The cost of 93 meter of plastic is Rs.1395.
By using the unitary method first to find the cost of 1 meter of that plastic as:
Cost of 93m of the plastic------\[Rs.1395\]
\[\therefore \]Cost of 1m of the plastic-----\[\dfrac{{1395}}{{93}} = Rs.15\]
Now, find the cost of 105 meter of plastic which would be required, hence
The cost of 105m of plastic-----\[ = \dfrac{{1395}}{{93}} \times 105 = 15 \times 105 = Rs.1575\]
So we can say that the total amount required to buy 105m of plastic is Rs.1575.

Note: To find the cost of a given unit of a product we always try to know the cost of a single unit of that product and the cost is found for the required numbers of units.