Challenge 3: A Four-Band Nested IF for Temperature — Solution Walkthrough

Formula for C2:
  =IF(A2>=30,"Hot",IF(A2>=20,"Warm",IF(A2>=10,"Cool","Cold")))

Trace for A2 = 25:

Step 1 — outermost IF: is A2>=30?
  25>=30  →  FALSE
  Since this is false, the whole formula's result becomes whatever
  the THIRD argument evaluates to — which is itself another IF, not
  a plain value yet: IF(A2>=20,"Warm",IF(A2>=10,"Cool","Cold"))

Step 2 — middle IF: is A2>=20?
  25>=20  →  TRUE
  Since this is true, this IF immediately returns its second
  argument: "Warm" — and because this whole middle IF was the value
  the outer IF's false-branch needed, "Warm" becomes the final result
  of the entire formula. The innermost IF (checking >=10) is never
  even evaluated at all.

Final result: "Warm"

Explanation of why "Hot" doesn't fire:

25 is genuinely below the "Hot" threshold of 30, so the first
condition correctly fails and control moves on to check the next
band down. This is exactly the same "descending order, each check
only runs if every earlier one already failed" logic this chapter's
own grading-formula example demonstrates — as long as the thresholds
are written from highest to lowest, each band only needs to rule out
everything above it, never everything below it too.

Notes:
- If the formula had mistakenly checked A2>=10 FIRST instead of last,
  25 would have matched that very first condition (since 25 is
  indeed >=10) and incorrectly returned "Cool" — this is why
  threshold order matters enormously in a nested IF chain built this
  way, and why the highest threshold must always be checked first.
- The formula has three opening parentheses after IF and needs
  exactly three closing parentheses at the very end — )))  — one
  per IF, matching this chapter's own warning about parenthesis
  counts in nested formulas.