###Human: A water tank has a capacity of 4000 gallons. Mack connects a pipe to the tank that fills the tank with water at the rate of 10 gallons per hour. How long will it take to fill the tank to 3/4 of its capacity?, ### Assistant: 3/4 of the water tank is 3/4*4000 = 3000
If the pipe fills the tank with water at the rate of 10 gallons per hour, it will take 3000/10 = 300 hours to fill the tank to 3/4 of its capacity 
 So the answer is :  300