Mathematical Puzzles
Hard
2 min
A tank contains 90 litres of water. One-third of the water is removed and replaced with an equal amount of clean water. How much of the original water remains?
Hint
One-third is removed only once.
Answer
60 litres.
Explanation
One-third of 90 is 30 litres. Therefore 90-30=60 litres of the original water remains.
Step-by-Step Solution
Removed = 90÷3=30L.
Original water remaining = 90-30=60L.
Original water remaining = 90-30=60L.