Question

A bottle contains $100\%$ phenyl. $\frac{1}{3}$ of it is replaced with water. The operation is repeated 4 times. What is the ratio of phenyl: water after the last operation?

• A. 16:81
• B. 1:5
• C. 14:82
• D. None of these

Answer 1

The correct option is D None of these

Option (d)

$\frac{LiquidAlefttaken{n}^{th}operation}{InitialquantityofAinthevessel}=\frac{(a-b{)}^n}{a^n}$

Amount of phenyl remaining $={(1-\frac{1}{3})}^4=\frac{16}{81}$

Therefore, ratio or phenyl:water = 16:65. (81-16=65)