Abathtub contains 15 gallons of water. the circular drain opening of the tub has a radius of 21 mm. what is the approximate circle circumference of the drain opening?

The equation m = 19.32v can be used to find the mass m in grams of a pure gold coin with volume v in cubic centimeters. carl has a coin with a mass of 37.8 grams. the coun's volume is 2.1 cubic centimeters. could the coin be pure gold? explain your reasoning. whoever answers this correctly gets marked brainliest! this is also worth a decent amount of points than normal questions!