Answer:
243 students
Step-by-step explanation:
First row: 3 students
Second row: 9 students (3^2)
Third row: 27 students (3^3)
Fourth row: 81 students (3^4)
Fifth row: 243 students (3^5)
The basic logic behind this question is that each row is a "cube" --> the fifth row is 3 ^5, meaning 3 x 3 x 3 x 3 x 3 (equals 243!!)
Knowing this, you could even solve for how many kids are in, say, the 12th row. It would just be 3^12.