Cratering Evidence Throughout the Solar System Indicates That the Frequency

Multiple Choice

Cratering evidence throughout the Solar System indicates that the frequency of asteroid impact is inversely proportional to the cube of the diameter of the asteroid (that is, 1/D³) .The 2013 Chelyabinsk meteor was around 20 meters in diameter and impacts of this size are expected once every 60 years, on average.If the Tunguska impact was a meteor around 100 meters in diameter, what is the expected average time between impacts of that size?

A) 1 every 220,000 years
B) 1 every 7,500 years
C) 1 every 1,200 years
D) 1 every 180 years
E) 1 every 0.5 year (2 a year)