Q1.
How much rice would feed a family of four for a month?
Answer
About 70–80 kg of uncooked rice — under the deliberate assumption that all the family's calories come from rice alone.
energy needed per adult ≈ 2000 – 2500 kcal per day, take 2250 kcal
family of four (2 adults + 2 children) ≈ 4 × 2250 kcal ≈ 9000 kcal per day
100 g of uncooked rice gives about 350 kcal when cooked
rice per day = 9000 kcal ÷ (350 kcal / 100 g)
= 9000 / 3.5 g ≈ 2570 g ≈ 2.6 kg per day
rice per month = 2.6 kg × 30 = about 77 kg
family of four (2 adults + 2 children) ≈ 4 × 2250 kcal ≈ 9000 kcal per day
100 g of uncooked rice gives about 350 kcal when cooked
rice per day = 9000 kcal ÷ (350 kcal / 100 g)
= 9000 / 3.5 g ≈ 2570 g ≈ 2.6 kg per day
rice per month = 2.6 kg × 30 = about 77 kg
Now do what the box actually asks — check whether the answer makes sense:
- 100 g for a month is clearly far too little (that is one small meal).
- A few tonnes is far too much (a tonne of rice would fill a small room).
- 77 kg is roughly one and a half of the 50 kg sacks sold in the market — a quantity a family could actually store and finish. The estimate passes.
Why it happens: the answer comes out about twice what a real family buys, and that is not an error — it is the assumption showing itself. Real meals also contain dal, oil, vegetables and milk, and oil alone carries about 900 kcal per 100 g. Since only part of the 9000 kcal now has to come from rice, the rice figure falls to roughly 35–40 kg a month, which is close to what households really use. That is the whole value of an estimate: it is not meant to be exact, but it tells you the answer lies in tens of kilograms, and it makes the assumption that produced it visible and correctable.
Check it yourself: find the calorie value printed on a rice packet and the number of people in your home, and redo the three lines above. If your answer lands anywhere between 30 kg and 100 kg a month, your reasoning is sound — the exact number was never the point.