In what ratio must rice at Rs. 9.30 per kg be mixed with rice at Rs. 10.80 per kg so that the mixture be worth Rs10 per kg?Options :8:77:95:97:5

To solve this problem, we can use the method of allegation, which is a rule of mixture to find the ratio in which two or more ingredients at the given price must be mixed to produce a mixture of a desired price.

Here are the steps:

1. Write down the cost of the cheaper and dearer ingredients on the left side. In this case, Rs. 9.30 per kg and Rs. 10.80 per kg respectively.

2. Write down the mean value (the cost of the mixture) in the middle. In this case, Rs. 10 per kg.

3. Subtract diagonally and write down the differences on the right side. The difference between Rs. 10.80 and Rs. 10 is Rs. 0.80, and the difference between Rs. 10 and Rs. 9.30 is Rs. 0.70.

4. The required ratio of the mixture is the ratio of these differences. So, the ratio in which the two types of rice should be mixed is 0.80 : 0.70, which simplifies to 8 : 7.

So, the rice at Rs. 9.30 per kg and the rice at Rs. 10.80 per kg should be mixed in the ratio 8 : 7 to get a mixture worth Rs. 10 per kg.