The Man and His Oil: A Temple Riddle of Doubling and Donation

 

Problem Statement

A man has some oil.

  • At the first temple, his oil doubles, and then he donates 5 litres.

  • At the second temple, his oil again doubles, and he donates 5 litres.

  • At the third temple, his oil once more doubles, and after donating 5 litres, his oil is completely finished.

Question: How much oil did he have initially?

🧮 Step‑by‑Step Solution

Let the initial oil = x litres.

At the First Temple

  • Oil doubles → 2x.

  • He donates 5 litres → remaining = 2x−5.

At the Second Temple

  • Oil doubles again → 2(2x−5)=4x−10.

  • He donates 5 litres → remaining = 4x−15.

At the Third Temple

  • Oil doubles again → 2(4x−15)=8x−30.

  • He donates 5 litres → remaining = 8x−35.

  • This equals 0 (oil finished).

So:

8x−35=0
8x=35
x=358=4.375 litres

✅ Final Answer

The man initially had 4 litres 375 millilitres (4 kg 375 g) of oil.

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