Question

If 7kg onions cost 140 rupees, how much must we pay for 12 kg onions?

Answer 1

Hint: By the given data of price of 7kg onions which is Rs. 140, first find the price of 1 kg onion by dividing the price by 7. Then to find the price of 12 kg onions, multiply it by 12 to get the cost.

Complete step-by-step answer:
In the question, we are given the price of 7 kg onions which is stated as Rs. 140 and by this given information, we have to tell how much we have to pay for 12 kg onions. We will do the problem using a method called the unitary method.
Now, before proceeding let’s learn something about the unitary method. In the unitary method, we will learn how to find the value of a unit from the value of a unit. When we go to the market to buy any particle, we ask the shopkeeper to tell the price of the article. This is called the unit price. We calculate the price of the number of articles we want to buy with the help of this unit price. Sometimes, we calculate unit price when the price of a multiple is given. The method to calculate the price of the required articles is called the unitary method.
Generally, first, we find the value of one article from the value of multiple and then we find the value of the desired number of articles from the value of one. Usually, the method includes multiplication and division.
So, in this question, the cost of 7 kg onions was Rs. 140. So, we can say that the cost of 1kg onions will be \[\dfrac{Rs.140}{7}=Rs.20.\]
Now, we were asked for the cost of 12 kg onion, so the cost will be 12 times the cost of 1 kg onion which is \[12\times Rs.20=Rs.240.\]
Hence, the cost of 12 kg onions is Rs. 240.

Note: If the cost of one object is given, we can find the cost of many objects by multiplying the cost of one object with the number of objects. If the cost of several objects is given, we can find the cost of one object by dividing the cost of several objects by the number of objects.