A block placed on an inclined plane of inclination 30" is released. It travels a distances. If the time taken by the block to slide on a rough incline is In times the time taken by the block to slide on a smooth incline, then the coefficient of friction between the block and rough incline is

Dear Student,
Your question is not clear and appears to be incomplete (number of times is not clear). Recheck your question or please be a little specific about the name of the chapter/textbook to which you are referring here so that we can provide you with some meaningful help.
Look forward to hearing from you again!
Regards