Two girls ate dinner together and then ordered iced tea. One girl drank very fast and finished five glasses while the other slowly drank just one. The slow drinker died from poison in the drinks, but the fast drinker survived. All the teas contained the same poison. How did the girl who drank the most survive?

Introduction / Context:
This is a classic lateral thinking and crime riddle about poison and timing. Two girls share a meal and then drink iced tea. One girl drinks extremely quickly and finishes five glasses, while the other slowly finishes only one. Surprisingly, the slow drinker dies of poisoning, and the fast drinker survives, even though all the drinks are said to contain poison. The puzzle asks how this is possible, which tests your ability to think beyond simple volume and focus on how the poison was delivered and when it entered the drink.

Given Data / Assumptions:

• Both girls drink iced tea from the same set of drinks.
• The fast drinker consumes five glasses quickly; the slow drinker sips one glass slowly.
• All the iced teas are described as containing poison.
• The slow drinker dies, the fast drinker lives.
• We assume no hidden immunity or magical resistance; the solution must rely on the method and timing of poisoning.

Concept / Approach:
The central concept is that the poison is not evenly mixed in the liquid from the beginning. Instead, it is hidden in the ice cubes and only becomes dangerous once the ice has melted and mixed with the tea. If a person drinks very fast, they finish the tea before much of the ice melts, so the poison stays largely trapped in the cubes. A slow drinker, however, gives the ice enough time to melt, releasing the poison into the drink and leading to poisoning. Thus, the survival of the fast drinker is explained by the fact that she consumed the liquid before the poison dissolved into it.

Step-by-Step Solution:
Step 1: Note that both girls are drinking iced tea, which contains ice cubes that melt over time. Step 2: Recognize that the puzzle mentions poison in the drinks but does not specify whether it is in the liquid or the ice. Step 3: Consider the behavior of the fast drinker. She finishes five glasses quickly, so the ice in her glasses does not have much time to melt. Step 4: Consider the slow drinker, who nurses a single drink. As she sips slowly, the ice cubes in her glass have plenty of time to melt completely. Step 5: Infer that the poison was frozen into the ice cubes rather than mixed into the tea itself. Step 6: Conclude that the fast drinker mostly consumed tea with solid ice, so she took in very little poison, while the slow drinker eventually drank all the melted ice, absorbing a lethal dose.
Verification / Alternative check:
To verify, imagine repeating the scenario. If the poison is in the tea, the girl who drinks more tea should be more affected, which contradicts the outcome. However, if the poison is concentrated in the ice, a fast drinker who finishes drinks before melting is largely safe, while a slow drinker who gives the ice time to melt is at high risk. Many riddle books present this exact story with the explanation that the poison was in the ice, confirming that this is the standard solution.

Why Other Options Are Wrong:
The fast drinker had already built up immunity: This is an invented medical detail with no support in the puzzle and not a typical lateral thinking answer.
The fast drinker secretly switched glasses: There is no mention of switching in the riddle, and this would not explain why all the drinks are said to contain poison.
The poison only affects people who drink less than two glasses: This is arbitrary and contradicts the normal behavior of poisons, which depends on dose, not on number of glasses.

Common Pitfalls:
A common mistake is to focus only on the total volume of tea drunk and assume that more tea must equal more poison. Another pitfall is to invent unexplained medical or magical reasons for immunity. Instead, lateral thinking problems like this reward you for considering different ways the poison might have been delivered. Once you realize that ice melts over time and that poison can be frozen in ice, the puzzle becomes straightforward.

Final Answer:
The girl who drank the most survived because the poison was frozen in the ice, and she finished her iced tea before the ice melted, while the slow drinker waited long enough for the poisoned ice in her glass to melt and mix into the drink.