Analytical and observational type questions are those that can only be worked out with your observational and analytical skills. For the same reason, there is no particular theory for this section. All we can do is, get a command over these tricky questions through practice. It should be noted that most of the questions in this section can be done in less than a minute and practicing more questions will help you acquire that speed.
In some questions, drawing Venn-diagrams can help you visualize the given condition easily. First, let’s discuss how to draw a Venn-diagram.
To draw a Venn diagram:
Step 1: Identify the elements in the question.
Step 2: Identify the categories you have to put these items into.
Step 3: List out the items that fall into both categories, each category, and neither.
Step 4: Draw universal set, represent it as a rectangle. Mark number of elements in the universal set.
Step 5: Draw circles corresponding to each category you identified inside the universal set. Label each circle according to the category you want it to represent. Enter number of items common to each category in the overlapping portion of circles with the respective labels. Insert other details in other parts of the circle. Also mark number of items not belonging to any (= number of objects in universal set – sum of items in categories) in the space outside of these circles and inside universal set (if required).
“For detailed theory, refer the book “CSIR-NET General Aptitude – A New Outlook”