There are 45 students in a row. Rohan is 18th from the left and Aman is 20th from the right. How many students are between them?

The correct answer is Option 7.

Let's solve this step-by-step to find the total number of students sitting between Rohan and Aman.

Step 1: Understand the given data
Total number of students in the row = 45
Rohan's position from the left end = 18th
Aman's position from the right end = 20th

Step 2: Find Rohan's position from the right end
To determine whether Rohan and Aman overlap, let's find Rohan's position from the right end using the formula:

$\text{Position from right}=\text{Total students}-\text{Position from left}+1$

$\text{Rohan's position from right}=45-18+1=28+1=29\text{th}$

Step 3: Calculate the number of students between Rohan and Aman
Since Rohan's rank from the left is 18 and Aman's rank from the right is 20, the sum of their ranks from opposite ends is:

$18+20=38$

Since the sum of their ranks (38) is less than the total number of students (45), Rohan and Aman do not overlap. Therefore, the number of students between them is calculated as:

$\text{Students between them}=\text{Total students}-(\text{Rohan's position from left}+\text{Aman's position from right})$

$\text{Students between them}=45-(18+20)$

$\text{Students between them}=45-38=7$

Thus, there are 7 students sitting between Rohan and Aman.