Q2. Pipe A fills a tank in 8 hours, Pipe B fills it in 12 hours. Pipe C is a leak that can empty the full tank in 30 hours. All three are opened together but the leak C is switched on only after 2 hours (A and B start at t=0, C starts at t=2). How long from start will the tank be filled?

Q3. If \( x+y =10 \) and \(x^2+y^2=58 \), find \(x ^3+ y^3 \)

Q4. A container has milk and water in ratio 7:3. 30 liters of mixture is taken out and replaced by water. After this operation the new ratio becomes 5:5 (i.e., equal). What was the total volume of the mixture originally?

Q5. A boat covers 30 km upstream and returns 30 km downstream in 5 hours 30 minutes (i.e. 5.5 hours). The stream’s current is 3 km/h. Find the speed of the boat in still water (in km/h).