When Jacob closes the drain of his bathtub and turns on the cold water

Let the total capacity of the bathtub be 1 unit of water.
Define the flow rates for each source in units per minute**.

The individual filling rates
- Cold water spigot fills the tub in 3 minutes 40 seconds = 11/3 minutes
→ Rate of cold water: \(\frac{1}{\frac{11}{3}} = \frac{3}{11}\) units/min
- Hot water spigot fills the tub in 5 minutes 30 seconds = 11/2 minutes
→ Rate of hot water: \(\frac{1}{\frac{11}{2}} = \frac{2}{11}\) units/min

Drain rate
- Drain empties a full tub in 11 minutes
→ Drain rate: \(\frac{1}{11}\) units/min

Net filling rate
\(\left(\frac{3}{11} + \frac{2}{11} - \frac{1}{11} \right) = \frac{4}{11}\) units/min

Since the bathtub needs **1 unit** of water to be full: \( \text{Time} = \frac{1}{\frac{4}{11}} = \frac{11}{4} = 2.75 \) minutes

Option B - 2 min 45 sec