Let \( x \) represent the cost of tuition, room, and board at 2-year private colleges. According to the information provided, the cost at 2-year public colleges is 30% of the cost at private colleges. This can be set up as the equation:
\[ 0.30x = 4800 \]
To find \( x \), we can solve for it by dividing both sides of the equation by 0.30:
\[ x = \frac{4800}{0.30} \]
Calculating the right side:
\[ x = 4800 \div 0.30 = 4800 \div 0.3 = 16000 \]
Thus, the cost of tuition, room, and board at 2-year private colleges is
\[ \boxed{16000} \]