Question

A tin container contains 50 litres of cow milk. From this container 5 litres cow milk was taken out and replaced with soya milk. This process was repeated further two more times. How much cow milk is there in the container now?

• A. 364.5 litres
• B. 36.45 litres
• C. 3.645 litres
• D. 40 litres

Hint:

Cow milk left = \(50(1 - 5/50)^3\).

Answer 1

The Correct Option is B

Step 1: Track the amount step by step.
Start with 50 litres of cow milk.

Step 2: After the first replacement.
Cow milk = \(50 - 5 = 45\) litres.

Step 3: After the second replacement.
The mixture is 45 parts cow milk in 50. Removing 5 litres takes out \(5 \times \frac{45}{50} = 4.5\) litres of cow milk. Left: \(45 - 4.5 = 40.5\) litres.

Step 4: After the third replacement.
Removing 5 litres takes out \(5 \times \frac{40.5}{50} = 4.05\) litres of cow milk. Left: \(40.5 - 4.05 = 36.45\) litres.

Final Answer:
The amount is 36.45 litres, option 2. \[ \boxed{36.45} \]