Aptitude - Alligation or Mixture - Discussion

Discussion Forum : Alligation or Mixture - General Questions (Q.No. 11)
11.
Find the ratio in which rice at Rs. 7.20 a kg be mixed with rice at Rs. 5.70 a kg to produce a mixture worth Rs. 6.30 a kg.
1 : 3
2 : 3
3 : 4
4 : 5
Answer: Option
Explanation:

By the rule of alligation:

Cost of 1 kg of 1st kind Cost of 1 kg of 2nd kind
720 p Mean Price
630 p
570 p
60 90

Required ratio = 60 : 90 = 2 : 3.

Discussion:
31 comments Page 4 of 4.

Sylvester OgboluOtutu said:   22 hours ago
The ratio is 2 : 3

Representations:
Using x to represent the quantity of rice at Rs 7.20 per kilogram and y to represent the quantity of rice at Rs. 5.70 per kilogram.

It is given that.

7.20x + 5.70y = 6.30(x + y).
7.20x + 5.70y = 6.30x + 6.30y.
7.20x - 6.30x = 6.30y - 5.70y.
0.9x = 0.6y.
9x = 6y.
9x/9y = 6y/9y.
x/y = 2/3.
The ratio of x : y is 2/3 or 2 : 3.

Checking:
Rs. 7.20 × 2 = Rs. 14.40.
Rs. 5.70 × 3 = Rs. 17.10.
Rs. 14.49 + Rs. 17.10 = Rs. 31.50.
Rs. 31.50 ÷ 5 = Rs. 6.30 (Checked).


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