Ya I got the same. Bro jus calculate vel at mean using WET. Then you can find amplitude using the vel at mean. Then toh finding time is not too hard.
It’s pretty lengthy tho… Idk if there is a better method.
@TheOverlord I solved a similar problem yesterday you may check that. The block and liquid shm matching question.( Last part of the matching when density is 2/3)
Doubts from SHM and Electrostatics
Try to understand the solution and then you may want to try this question on your own. I think it would be better for you in this way.