An Argument: Good or Bad?

There are many everyday examples of of good valid argument. One argument could be about shoes for instance. My friend Christine has seven pairs of shoes. There are seven days in a week. Therefore she has a pair of shoes for everyday of the week. This is a good valid argument because both premises are true. Also, both premises eliminate the fact that the conclusion cannot be false. Therefore this is a valid argument.

My friend Alex does not study for his final exams and does horrible. The final exams are based on the readings in the book. Therefore due to Alex not studying, he fails his final exams. This is a good valid argument because both premises are plausible and are more plausible than the conclusion. Also, both premises eliminate the thought the conclusion is not false. Therefore this is also a good argument.