Hi Millie!
It is my understanding that you want to guess time for given values.
You can try 'interp1' function for your data.
You can read more about this function on https://in.mathworks.com/help/matlab/ref/interp1.html?searchHighlight=interp1&s_tid=srchtitle_interp1_1
I hope this information helps you.
If not, please provide a detailed description of your problem.
Thanks
