The temperature at which water leaves the boiler is?

The average setting for a gas-powered hot water boiler is 180°F. This provides the appropriate level needed for most cold weather temperatures. If you can raise the temperature manually, do not set it any higher than 210°F (which is often the limit), and try to remain down at 190°F if you need the extra heat.

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures