Multiple choice

From a tank of petrol, which contains 200 litres of petrol, the seller replaces each time with kerosene when he sells 40 litres of petrol (or its mixture). Everytime he sells out only 40 litres of petrol (pure or impure). After replacing the petrol with kerosene 4th time, the total amount of kerosene in the mixture is

  1. 124.36

  2. 112.36

  3. 118.08

  4. 139.24

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Formula for replacement: Final amount = Initial * (1 - removed/total)^n. Final petrol = 200 * (1 - 40/200)^4 = 200 * (0.8)^4 = 200 * 0.4096 = 81.92. Kerosene = 200 - 81.92 = 118.08.

AI explanation

Use the replacement formula to find the remaining petrol after 4 replacements, calculated as 200 multiplied by (1 minus 40 divided by 200) raised to the power of 4. This simplifies to 200 multiplied by 0.8 raised to 4, which equals 200 multiplied by 0.4096, giving 81.92 litres of petrol left. The total amount of kerosene is the total capacity minus the remaining petrol, which is 200 minus 81.92, resulting in 118.08 litres.

Keep practicing — related questions