Two solutions, A and B, are produced by mixing milk and water in

%milk * total volume of solution = volume of milk

Method 1,
I,II Each statement insufficient because two variables found in one equation

Combined statement I&II,
--------------%Milk------ total volume of solution---- volume of milk
A--------------60---------A---------------------------------X
B--------------70---------80-A-----------------------------50-X
------------------------------------------------------------------------
Combined -------------- 80--------------------------------50
-------------------------------------------------------------------------

Statement I & II,
60%A = X,
70%(80-A)=50-X,

I -> II, solved A and X.
I,II Two equations , two variables found - sufficient
Ans: C



Method 2,
I,II Each statement insufficient because two variables found in one equation

combined statement I&II,
--------------%Milk------ Total volume of solution---- Volume of milk
A--------------60---------A-------------------------------60A
B--------------70---------B-------------------------------70B
------------------------------------------------------------------------
Combined -------------- 80------------------------------50
-------------------------------------------------------------------------

Statement I & II,
60A + 70B = 50
A+B=80,
I -> II, solved A and B.
I,II Two equations , two variables found - sufficient
Ans: C

It is simple question just read the statements and make the equation:

what is given in question:

Two solutions A & B are made up of 60% milk and 70% milk resp and rest is water i.e 40% water in A and 30% water in B.

now we need to find out volume of solution A?

statement 1:

0.6A + 0.7B = 50

simplifying,
6A + 7B =500

1 equation 2 unknown so insufficient.

Statement 2:

A+B = 80

1 equation 2 unknown so insufficient.

Combining statement 1 and 2,

2 equation 2 unknown so sufficient.

simplifying we get,
A=60

hence option C is the answer.

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