Answer:
There were 14 students in the circle
Step-by-step explanation:
* Lets explain how to solve the problem
- The students stood in a circle
∴ The line joining each two opposite students is the diameter
 of the circle
- The 6th student was directly across from the 13th student
∴ The 6th student is opposite to the 13th student
- Lets count how many students between 6th student and
 13th student
∵ 7th , 8th , 9th , 10th , 11th , 12th students between the 6th
 student and 13th student
∴ There are 6 students between them
- Lets count how many students between 13th student and
 6th student
∵ 14th , 1st , 2nd , 3rd , 4th , 5th students between the 13th
 student and 6th student
∴ There are 6 students between them
∵ There are 6 students between 6th and 13th
∵ There are 6 students between 13th and 6th
∵ There are 2 students in 6th and 13th
∴ The number of the students = 6 + 6 + 2 = 14
∴ There were 14 students in the circle
