Initially 1 m string is hanging and 3m is on the table. Now string start burning from both ends such that burning rate at A is 5 times that of B. Find the time when slipping occurs if burning rate at B is 20 cm/sec.

1) | 0001 | |||
2) | 0002 | |||
3) | 0003 | |||
4) | 0004 |