What is the number of type-2 widgets produced, if the total number of widgets produced is 20,000? The company produces only two types of widgets.
I. If the production of type-1 widgets increases by 10% and that of type-2 decreases by 6%, the total production remains the same.
II. The ratio in which type-1 and type-2 widgets are produced is 2 : 1.

if the question cannot be answered even with the help of both the statements taken together.

if the question can be answered by any one of the two statements.

if each statement alone is sufficient to answer the question, but not the other one (e.g. statement I alone is required to answer the question, but not statement II and vice versa.

if both statements I and II together are needed to answer the question.