The fundamental frequency of a closed organ pipe is equal to the first overtone frequency of an open organ pipe. If length of the open pipe is \( 60 \, \text{cm} \), the length of the closed pipe will be:
\( 45 \, \text{cm} \)
\( 15 \, \text{cm} \)
\( 60 \, \text{cm} \)
\( 30 \, \text{cm} \)