Among the globular clusters orbiting a distant galaxy, one is moving at 420 km/s and is located 11 kpc from the center of the galaxy.

Among the globular clusters orbiting a distant galaxy, one is moving at 420 km/s and is located 11 kpc from the center of the galaxy. Assuming the globular cluster is located outside most of the mass of the galaxy, what is the mass of the galaxy? (Hint: Use the formula for circular velocity . Remember to convert units to meters and kilograms.) Express your answer in billions of solar masses.