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?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 36.45 litres
Each time 5 litres of the mixture are removed from 50 litres, so \( \frac{5}{50}=\frac{1}{10} \) of the cow milk present goes out and \( \frac{9}{10} \) remains. The process is done 3 times in all (once, then two more times).
\( \displaystyle \text{Cow milk left}=50\left(1-\frac{5}{50}\right)^3 \)
\( \displaystyle =50\times\left(\frac{9}{10}\right)^3 \)
\( =50\times 0.729 \)
\( =36.45\ \text{litres} \)
CBSE Applied Mathematics (Class XII):
Alligation and Mixture
