Quantitative Aptitude – Arithmetic – Mixtures – The strength of a salt solution is p%

Slot -2 – Quantitative Aptitude – Arithmetic – Mixtures – The strength of a salt solution is p%

The strength of a salt solution is p% if 100 ml of the solution contains p grams of salt. If three salt solutions A, B, C are mixed in the proportion 1 : 2 : 3, then the resulting solution has strength 20%. If instead the proportion is 3 : 2 : 1, then the resulting solution has strength 30%. A fourth solution, D, is produced by mixing B and C in the ratio 2 : 7. The ratio of the strength of D to that of A is?

a) 1 : 3

b) 2 : 5

c) 1 : 4

d) 3 : 10

Answer: a) 1 :3

Solution:

let the concentration of A, B & C are a% , b% & c% respectively .

Then (a+2b+3c )/600=20/100=1/5

a+2b+3c=120——1)

And (3a+2b+c )/600=30/100=3/10

3a+2b+c=180——-2)

By eq 1)/ eq 2) , (a+2b+3c )/(3a+2b+c )=2/3
3a+6b+9c=6a+4b+2c

(2b+7c)/a=3

So correct answer : a) 1 :3

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