If she has not sent it off, confront her. Ask her if it is all her own words, word for word, or if she got loadsss of 'help'?
If she has sent it off, tell her you recognise her PS was similar to many online. After all, you are both applying for the same course so its not like she would question why you read some Adult Nursing PS online.
If she has sent it off and you choose not to let her know the consequences she may face, when she does face the consequences, you are gonna have to fake the whole 'wow how was that possible?'. Of course she knew what she was doing but maybe she thought she was being subtle. At least this way she will be prepared for what is yet to come.
If you reckon 50% of it was plagiarised, then she has no chance of getting away with it because I think anything more than 10% is picked up by the system.