I have a 3rd edition ACT red book, and my friend gave me a 2nd edition ACT red book. I thought I could use the 2nd edition for extra practice. Would the practice tests in the older edition be adequate for the ACT now or would they be outdated somehow?
No they should probably be fine. I’m not sure what could be wrong with it.
Both books are old, but are helpful in that they are real ACT tests. The ACT Black book would be a good companion for the third edition.
The 3rd edition contains all of the second edition plus additional tests. So you have some duplicates.
ACT also releases practice tests.