Question: Combining Solutions W and X

Comment on Combining Solutions W and X

50+0.8x = 0.4(250+x)
gmat-admin's picture

Yes, that's the equation we derived in the video.

Hi Bent,

I find your approach of solving Mixture problems with diagrammatic representation very easy.Thank You.

Can you please help with the following problem:

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
gmat-admin's picture

Tricky question!

If you like the mixture technique that's shown in the video, then here's one approach:

Let's say the alloys are composed of gold and silver (in that order)

So, alloy A has a gold to silver ratio of 5 : 3
In other words, this alloy is 5/8 gold

Alloy B has a gold to silver ratio of 1 : 2
In other words, this alloy is 1/3 gold

"A new alloy X is formed by mixing the two alloys A and B in the ratio 4 : 3"

Let's combine 4 cups of alloy A with 3 cups of alloy B.

Since alloy A is 5/8 gold, then the amount of gold in 4 cups of alloy A = (5/8)(4) = 5/2 = 2.5 cups

Since alloy B is 1/3 gold, then the amount of gold in 3 cups of alloy B = (1/3)(3) = 1 cup

So, the TOTAL amount of combined gold = 2.5 + 1 = 3.5 cups.

The new mixture has a TOTAL volume of 7 cups.

If 3.5 cups is gold, then the remaining 3.5 cups must be silver.

"What is the ratio of the composition of the two basic elements in alloy X ?"

We get 3.5 : 3.5, which is the same as 1:1

Answer: A

:D :D
I had a smile going through your explanation.
You make tricky things so easy! Thankieeee

Brent,

Could you explain me the exercise #201 of OG17, please?

Thanks,
Pedro

Hi Brent,
can you please solve this question, using the technique as in above video.
Jackie has two solutions that are 2 percent sulfuric acid and 12 percent sulfuric acid by volume, respectively. If these solutions are mixed in appropriate quantities to produce 60 liters of a solution that is 5 percent sulfuric acid, approximately how many liters of the 2 percent solution will be required?

Thanks

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