Mixture of mixtures

 In alloy P, if the total weight of P is 11 gm, then the weight of gold is 4gm, and the weight of silver is 7 gm. In alloy Q, if the total weight of Q is 12 gm, then the weight of gold is 7 gm, and the weight of silver is 5 gm.
L.C.M of (11,12) = 132
Therefore, if the weight of the alloy P is 132 gm => (48 gm gold and 84 gm silver). If the weight of the alloy Q is 132 gm => (77 gm gold and 55 gm silver).
It is given that quantities of alloys from P and Q melted are in the ratio of 4:3, which implies If the quantity of alloy P that is melted = (4*132) gm, then the quantity of alloy Q that is melted =(3*132) gm.

In (4*132) gm of alloy P, the quantity of gold is (4*48) = 192 gm, and the quantity of silver is (4*84) = 336 gm.
In (3*132) gm of alloy Q, the quantity of gold is (77*3) = 231 gm, and the quantity of silver is (55*3) = 165 gm.
Hence, the total quantity of silver in alloy R is (336+165) = 501 gm, and the total quantity of gold in alloy R is (192+231) = 423 gm.

Hence, the ratio of silver to gold in alloy R is 501:423 = 167:141
The correct option is D

Let the size of each container be 630 liters,
Therefore, in first container amount of milk and water is 360 and 270 liters respectively.
In Second container amount of milk and water is 350 and 280 liters respectively.
In Third container amount of milk and water is 210 and 420 liters respectively.
In Fourth container amount of milk and water is 180 and 450 liters respectively.
Size of the big vessel = 4.2*630 = 2646 liters.
Amount of milk in this vessel = 360+350+210+180 = 1100 liters and hence, amount of water in this vessel is = 2646-1100 = 1546 liters
Therefore, the ratio of milk to water in the big vessel = 1100:1546