In a class of 42 students, Swati’s rank is 19th from the bottom. Purshottam is 6 ranks below Swati. What is Purshottam’s rank from the top?

The correct answer is 30th.

Let's find Purshottam's rank step-by-step:

Step 1: Identify the given information
Total number of students in the class = 42
Swati's rank from the bottom = 19th

Step 2: Find Purshottam's rank from the bottom
Purshottam is 6 ranks below Swati. In rank ordering, being "below" Swati means being closer to the bottom of the class. Therefore, we subtract 6 from Swati's rank from the bottom to find Purshottam's rank from the bottom:

$\text{Purshottam's rank from the bottom}=\; 19\; -\; 6\; =\; 13$

So, Purshottam is 13th from the bottom.

Step 3: Calculate Purshottam's rank from the top
To convert a person's rank from the bottom to their rank from the top, we use the following standard relationship:

$\text{Rank from the top}=\; (\text{Total students}-\text{Rank from the bottom})\; +\; 1$

Substituting the known values into this formula:

$\text{Purshottam's rank from the top}=\; (42\; -\; 13)\; +\; 1$

Simplifying the expression step-by-step:

$\text{Purshottam's rank from the top}=\; 29\; +\; 1\; =\; 30$

Therefore, Purshottam's rank from the top is 30th.