CAT (DILR) PYQs

There are four bottles. It is known that either one or two of these bottles contain(s)only P, while the remaining ones contain 85% P and 15% I. What is the minimum number of tests required to ascertain the exact number of bottles containing only P?

From a container filled with milk, $9$ litres of milk are drawn and replaced with water. Next, from the same container, $9$ litres are drawn and again replaced with water. If the volumes of milk and water in the container are now in the ratio of $16: 9$, then the capacity of the container, in litres, is

There are four bottles. Each bottle is known to contain only P or only I. They will be considered to be “collectively ready for despatch” if all of them contain only P. In minimum how many tests, is it possible to ascertain whether these four bottles are “collectively ready for despatch”?.