Kheer for 4 people needs 2 cups rice and 6 cups milk
Kheer for 4 people needs 2 cups rice and 6 cups milk. Now it must be made for 8. Rohan says just add 2 more cups of milk (6+2=8), since the people only doubled from 4, so 2 extra is enough. Is Rohan's method right?
Who do you think is right? Pick one.
The answer: No — double the milk too
Why
Rohan spotted the right fact — the people doubled — but then he ADDED to the milk instead of doubling it, and mixed up two different jumps. Doubling the eaters means doubling EVERY ingredient, each in its own proportion, not adding the same small number to each. People went 4 to 8, that's times-2; so rice goes 2 to 4, and milk goes 6 to 12 — not 6 to 8. Adding a flat '2' ignores that 6 was bigger to start, so it needs a bigger increase. Recipes scale by multiplying, because the RATIO of rice to milk must stay the same or the kheer turns wrong. Test: his way gives 4 cups rice but only 8 cups milk — a thicker, different dish than the 2:6 he started with. Rohan's not right: to serve double, multiply each ingredient by 2 — milk becomes 12 cups, keeping the recipe's ratio intact.
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