A town has 5000 teenagers, including both boys and girls, and each teenager requires 150 litres of water per day. The town water tank has dimensions 20 m × 15 m × 5 m. Assuming the tank is completely full and there is no wastage or additional inflow, for how many days will the water in the tank be sufficient for the town?

Introduction / Context:
This is a practical aptitude problem involving volume, unit conversion and daily consumption. We are asked to determine how long the water stored in a tank will last for a given population, each with a known daily requirement. Such questions test understanding of cubic volume, litres and basic division.

Given Data / Assumptions:
• Number of teenagers in the town = 5000.
• Water requirement per teenager per day = 150 litres.
• Tank dimensions = 20 m × 15 m × 5 m.
• The tank is assumed to be completely full initially.
• There is no extra water inflow or wastage during the period considered.

Concept / Approach:
The core idea is to convert the tank volume from cubic metres to litres, then compute the total daily requirement of the population in litres and finally divide total available water by daily consumption. One cubic metre equals 1000 litres, which is key for converting units correctly. The resulting quotient gives the number of days for which the water is sufficient.

Step-by-Step Solution:
Step 1: Compute the tank volume in cubic metres. Volume = length × width × height = 20 × 15 × 5 = 1500 cubic metres. Step 2: Convert cubic metres to litres. 1 cubic metre = 1000 litres, so tank volume = 1500 × 1000 = 1500000 litres. Step 3: Compute total daily water requirement of all teenagers. Daily requirement = 5000 × 150 = 750000 litres per day. Step 4: Find how many days the tank supply lasts. Number of days = total water ÷ daily requirement = 1500000 ÷ 750000 = 2 days.

Verification / Alternative check:
We can think of the tank as providing water for two days of consumption: 750000 litres per day times 2 equals 1500000 litres, which matches the tank capacity exactly. There is no leftover water and no shortage, confirming that 2 days is accurate.

Why Other Options Are Wrong:
4 days would require 4 × 750000 = 3000000 litres, which is double the available capacity. Similarly, 6 or 8 days would require even more water than the tank can hold. Therefore these options violate the basic volume constraint and cannot be correct.

Common Pitfalls:
Learners sometimes forget to convert cubic metres to litres and incorrectly use 1500 as total litres instead of 1500000. Others may miscalculate the daily requirement by using 15000 instead of 150 for each teenager. Carefully handling units and multiplication avoids these mistakes and leads directly to the correct answer.

Final Answer:
The water in the tank will be sufficient for 2 days.