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Two alloys A and B are composed of two basic elements. The

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Joined: 28 Jan 2017
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Re: Two alloys A and B are composed of two basic elements. The [#permalink]

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New post 25 Jun 2017, 03:15
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9



Edit: Source -> NOVA.


Hi

I am getting the below answer (23/18). Can someone explain me where I am making the mistake.
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Kudos [?]: 3 [0], given: 40

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Kudos [?]: 3 [0], given: 40

Re: Two alloys A and B are composed of two basic elements. The [#permalink]

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New post 25 Jun 2017, 05:18
CantDropThisTime wrote:
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9



Edit: Source -> NOVA.


Hi

I am getting the below answer (23/18). Can someone explain me where I am making the mistake.


I understood where did I make the mistake :) :)

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Re: Two alloys A and B are composed of two basic elements. The [#permalink]

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New post 25 Jun 2017, 07:54
For those who dont like alligation method, here is a another simple way to solve this:

Let A be of 4 kg and B be of 3 kg.

And, in A, first element is 5/8th of total and second element if 3/8th of total.
And in B, first element is 1/3rd of total and second element if 2/3rd of total.

Now, if we mix A and B,

First element = (5/8)*4 + (1/3)*3 = 7/2
Second element = (3/8)*4 + (2/3)*3 = 7/2

Thus, ratio of the 2 elements is 7/2 : 7/2 ie 1:1

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Re: Two alloys A and B are composed of two basic elements. The [#permalink]

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New post 25 Jun 2017, 11:44
Let E1 and E2 be elements one and two, respectively.

E1 (A) = 5
E2 (A) = 3
Total (A) = 8

E1 (B) = 1
E2 (B) = 2
Total (B) = 3

A in X = 4, which is half of Total (A) - so E1 and E2 in X from A are half of what they are in A.
B in X = 3, which is the same as in Total (B) - so E1 and E2 in X from B are the same as what they are in B.

E1 (X from A) = 5/2
E2 (X from A) = 3/2

E1 (X from B) = 1
E2 (X from B) = 2

[E1 (X from A) + E1 (X from B)] : [E2 (X from A) + E2 (X from B)] = 5/2 + 1 : 3/2 + 2 = 3.5 : 3.5 = 1 : 1. Ans - A.
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Re: Two alloys A and B are composed of two basic elements. The [#permalink]

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New post 06 Sep 2017, 09:27
farukqmul wrote:
Two alloys A and B are composed of two basic elements. The ratios of the compositions of the two basic elements in the two alloys are 5 : 3 and 1 : 2, respectively. A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3. What is the ratio of the composition of the two basic elements in alloy X ?

(A) 1 : 1
(B) 2 : 3
(C) 5 : 2
(D) 4 : 3
(E) 7 : 9



Edit: Source -> NOVA.


Element 1's proportion to the total of each liquid:
A -> 5/8
B -> 1/3

You want alloy X to be formed with 4/7 of it coming from liquid A and 3/7 coming from liquid B, hence:

5/8 * 4/7 + 2/3 * 3/7 = x (...) -> x = 7/14 which is 1/2. For element 1.
The proportion of element 2 coming from each liquids will be the same, and obviously the ratio will also be 1/2. Thus, answer A is the right one.

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Re: Two alloys A and B are composed of two basic elements. The   [#permalink] 06 Sep 2017, 09:27

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