Maria has lunch at a restaurant. if her bill was $12.25 and maria wants to leave a 20% tip, what is a reasonable estimate for the amount she should leave for the tip?

The pool holds 120,000 gallons of water.

Robert fills the pool at a rate of 10 gallons each minute.

That means for filling 120000 gallons, he will need = = 12000 minutes

If we convert this to hour, then in 1 hour, = 600 gallons  can be filled.

So, the rate in gallons per hour =   = 200 gallons per hour.  

Therefore, the rate at which Robert will fill the pool is 200 gallons per hour.

Yes the rate is constant.