Challenge 2: A Basic Adult/Minor IF Formula — Solution Walkthrough

Formula for B2:
  =IF(A2>=18,"Adult","Minor")

Trace for A2 = 17:
  Condition: A2>=18  →  17>=18  →  FALSE
  Since the condition is false, IF returns its third argument.
  Result: "Minor"

Trace for A2 = 18:
  Condition: A2>=18  →  18>=18  →  TRUE
  Since the condition is true, IF returns its second argument.
  Result: "Adult"

Explanation:

>= means "greater than or equal to," so the boundary value itself
(18) satisfies the condition and counts as an adult — this is a
common point of confusion in age-threshold formulas, since it's easy
to instead write a stricter > that would incorrectly classify exactly
18 as a "Minor."

Notes:
- If the requirement had instead been "18 counts as still a minor,
  19 is the first adult age," the correct operator would be a plain
  > instead of >=: =IF(A2>18,"Adult","Minor").
- Always double-check a boundary condition against the EXACT edge
  value mentioned in the requirement (here, 18) rather than just
  values clearly above or below it — the edge case is where > and >=
  actually produce different results.