Three liquids, A, B and C, are formed by mixing petrol and spirit in

­(1) The ratio of petrol and spirit in A and B are 2 : 3 and 3 : 4, respectively.

Without further information it is impossible to deduce the percetage of fuel in mixture C.

INSUFFICIENT

(2) If 20 liters of A, 21 liters of B and 27 liters of C are mixed, the resulting ratio of petrol and spirit is 29 : 39.

We are given the combined ratio of the mixture, however, without further information it is impossible to solve for percent of fuel found in mixture C.

INSUFFICIENT

(1+2)

Putting the statements together:

When we add the litres of the three mixtures we get: \(20+21+27 = 68\), and then we add the two parts of the ratio we also get \(29+39=68\). This most likely indicates that there is no simplification in the last ratio. 

Mixture A is \(\frac{2}{5}\) parts fuel. In the mixture of statement 2, it provides \(20*\frac{2}{5}=8\) litres of petrol and \(12\) litres of spirits.

Mixture B is \(\frac{3}{7}\) parts fuel. In the mixture of statement 2, it provides \(21*\frac{3}{7}=9\) litres of petrol and \(12\) litres of spirits.

Which means that Mixture C must contribute: \(29 - 8 - 9 = 12\)l litres of petrol and \(39 - 12 - 12 = 15\) litres of spirits.

Percent of petrol in Mixture C: \(\frac{12}{27}*100 = 44.444\)%

SUFFICIENT

ANSWER C­

­(1) The ratio of petrol and spirit in A and B are 2:3 and 3:4, respectively.
From, this information we are unable to find the accumulated quantity of liquid in A, B & C, nither the ratio of petrol and spirit in liquid C. So, option A & D are insufficient.

(2) If 20 liters of A, 21 liters of B and 27 liters of C are mixed, the resulting ratio of petrol and spirit is 29 : 39.
Since, the ratio of petrol and spirit are unknown, we cann't find out the percent of petrol in liquid C. So, option B is out.

Now, if we conbine these two information, we get, petrol and spirit in liquid A are in the ration 2:3. Meaning, Petrol 8 & Sprit 12. Using the same logic, in liquid B, Petrol 9 & Sprit 12 since the ration in 3:4.

Till now, we receive, Petrol 17 & Sprit 24. So, certainly, in liquid C, the quantity of Petrol & Sprit would be 12 & 15 and ratio 4:9.
So, the percent of petrol in liquid C is 44.44%.

In my opinion, answer C.­