How to access interpolated data to use as a variable??

See attached Mathcad file and xls file containing data.

I am trying to increase the number of time points in a field vs. time data file to then use in a subsequent calculation with the increased data points.  The time points are all less than 1.

I cannot figure out how to access the interpolated data to use in a subsequent calculation involving range variables.

Can the range variable to use as the indices be less than 1?  If not, how can this data be used in a time varying calculation?

Thanks for any help.

Reg Curry