Time Stretch/Tempo Question....please help

I just got an MPC 500 and this has been frustrating me.

I have a sequence set to a specific tempo, a sequence with a drum track and a track with a sample. I copied just the drums over to another sequence without that sample and recorded a different sample to use on this sequence. How do I get this sample to match the tempo that I have set for both sequences. I don't want the sequence to be a different tempo than the 1st one.

I know the obvious answer to this would be time stretch. But how do you match samples to the same tempo using time stretch? I don't know what the original tempo is for either of the samples. How can you set the new tempo the same for 2 samples and have them fill up the exact amount of time?

Help me.

you can match samples to the same tempo when you time stretch by making them the same length. if theres 4 bars in each of them and you make each one 5 seconds, then they will be the same tempo.