The star-forming portion of our Galaxy consists of a highly flattened circular disk about 30 (30,000 ) in diameter. Interstellar extinction limits our view to within a radius of about 5 kpc of the Sun. If supernovae occur in the Galaxy roughly once every 30 years, on average, and are uniformly spread throughout the disk, calculate how often we should expect to see a supernova. 1-about once every 150 years 2-about once every 270 years 3-about once every 600 years 4-about once every 1100 years