Tescos dilemma

Ok, I'm really on edge.

Last Saturday, I got called in by tescos for an interview at a local store. It's quite a big store and there were 12 checkout positions going.

I got a call the same day to go in on Monday this week for a work sample. We filled in a few forms and got told to stand by a checkout and ask customers if they needed help with packing and, if the agreed, to help them pack. I thought i did okay. My till was quite slow and I only packed bags for two/three customers as most of the customers said that they didn't have much and could do their own packing. After the work sample, they said that they would contact us soon. Yesterday, I politely rang and asked them when I should expect to hear from them by. The woman kindly said something among the lines of 'these things take a while' and that we should hear from them by Friday. It's Thursday morning and I'm really stressed because I'm really scared I haven't got it. It's a part time job and I'm a uni student, but I stressed in my application and the forms that I am very flexible in terms of time. I also took a peak at the list on the work sample day and it seems that they only selected 10 people for the work sample, even though there were 12 vacancies.