TASK DEFINITION: Given a paragraph about movies and a set of conversational questions and answers about the paragraph, say whether the passage contains sufficient information to answer the follow-up question. Say Yes if it is answerable; otherwise, say No. The paragraph has the prefix 'CONTEXT:'. Each conversation question has a prefix `Q:` followed by the answer prefix `A:`, and the follow-up question has a prefix `FOLLOWUP_Q:`.
PROBLEM: CONTEXT: Well, in answer to the first part: Yes, the water in which John Loomis (Chiwetel Ejiofor) was swimming/bathing when Ann Burden (Margot Robbie) came up to him is irradiated. Without getting too "spoilery", the area in which Ann lives seems to be one of very few (if not the only) radiation-free zones at the time of the story. However, the water in which John was swimming comes from outside of that area (the waterfall). As for the beneficial effects of the bath, I think the link to the "Silkwood Shower" reference by @Will-Feldman is probably as good an explanation as any. Try to get as much of the irradiated water off of the body as possible. John is obviously still going to be affected by his exposure, but there's no reason to allow more of the radiation to seep in if it can be prevented.  <sep>  Q: Why does Margot Robbie wash Chiwetel Ejiofor in Z for Zachariah? A: the water in which John was swimming comes from outside of that area (the waterfall  Q: Is there radiation in the water? A: irradiated  Q: What does irradiated mean? A: irradiated  <sep> FOLLOWUP_Q: Will scrubbing protect you from the radiation?

SOLUTION: No

PROBLEM: CONTEXT: Since becoming the Three Eyed Raven, Bran has the ability to remember, well, everything that's ever happened in Westeros, including how he fell from the tower (although given that Sam was able to tell him some, ahem, surprising news, it seems that he doesn't just "know" everything in the past). Bran also has a habit of repeating things he never could have heard people say, just as a subtle way of saying "just so you know, I know". As he throws Bran from the window, Jaime quips to Cersei, "The things I do for love". When Bran paraphrases this line back to Jaime while staring him in the eye in S8e2, it becomes clear to Jaime that Bran knows what happened. He does something similar with Littlefinger, quoting "chaos is a ladder" at him, despite it being impossible for him to have heard the original conversation.  <sep>  Q: When does Bran Stark remember Jaime pushing him? A: Since becoming the Three Eyed Raven, Bran has the ability to remember  <sep> FOLLOWUP_Q: What does he remember exactly?

SOLUTION: Yes

PROBLEM: CONTEXT: This is explained a little more in the Novel, and is easier to understand with the hindsight of knowing Plutarch Heavensbee was subversively finding ways to assist the tributes who were complicit in the revolution... It doesn't explicitly state 'Plutarch did this because of this and this...' because that would be terrible clunky writing, and Collins is a much better writer than most people will give her credit for... it just takes a little logic and deduction. The 'Lightning Tree' is in the section of the Arena which endures a lightning storm within its hour. The lightning tree introduces (naturally, without raising the suspicions of anyone else) the element of controlled, predictable burst of electricity in a pre-designated location, which obviously is of benefit to Beetee. Furthermore, it is a clear and concise way for the tributes to keep track of what time it is, even if they aren't anywhere near the section that is enduring it's 'hour'. It's the equivalent of Big Ben striking 12. It's never pro-filmically shown that Beetee had discussed a plan with Heavensbee beforehand, but it's interesting that Beetee is insistent on carrying around that spool of electrical wire throughout most of the film. It's quite an encumbrance to keep hold of, 'just in-case', so it could be inferred that Beetee had the plan all along.  <sep>  Q: Was there a purpose for the lightning tree in Catching Fire?

SOLUTION:
Yes