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:
32 comments Page 3 of 4.

Deepti said:   10 years ago
Thank you, your explanation was helpful.

Ajay said:   2 decades ago
How 60 & 90 came here?

MAZHAURL91BD said:   1 decade ago
Details solution:

Let, X kg mixture with take 7.20 and 1 kg mixture with take 5.70.

Then, Cost price of 1 kg mixture is (7.20x + 5.70)/(x+1).

According to the question:

(7.20x + 5.70)/(x+1) = 6.30.

=> 7.20x + 5.70 = 6.30x + 6.30.

=> 0.90x = 0.60.

=> x = 2/3.

Jas said:   1 decade ago
As per alligation rule they have written in wrong order.

Sumanth geras said:   1 decade ago
7.20(x)+5.70(y)/x+y = 6.30.

Here x and y are the ratio's in which they are mixed.

7.20(x)+5.70(y) = 6.30(x)+6.30(y).

On solving we get x:y = 2:3.

This is the easiest method for these kind of problems.

Pushpa said:   1 decade ago
Guys following rule of alligation we will get 3:2 (Cheaper quantity:Dearer quantity) as answer but in question it is asked the ratio of dearer qty to the cheaper one tats why answer will be 2:3 hope I have made my point clear!

Vaishnavi said:   1 decade ago
No its 2:3 only.
How it comes is that,

-> (6.30-7.20)=> -0.60.
-> (5.70-6.30)=> -0.90.

Upon equating them acc to allegations rule, you get,
0.2:0.3 which will be 2:3;

I guess it comes this way..am I right?

Oldman said:   1 decade ago
Let the ratio be x/1-x
Then
7.20 (1-x) + 5.70 x = 6.30
7.20 -7.20x + 5.70x =6.30
7.20-1.50x =6.30
7.20-6.30 /1.50 =x
0.90/1.50 = x
3/5 =x
1-x = 1-3/5 =2/5
x/1-x = 3/5 /2/5 = 3/2

Sakshi said:   1 decade ago
According to books cheaper price shoul b taken firtt then dearer. So I think answer is 3:2. Please clear my doubt m I right?

Hari said:   1 decade ago
How 630 came?


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