A certain radioactive isotope placed near a Geiger counter registers 120 counts per minute. If the half-life of the isotope is one day, what will be the count rate at the end of four days?

A) 30 counts/min
B) 15 counts/min
C) 10 counts/min
D) 7.5 counts/min
E) 5 counts/min


Answer: D

Physics & Space Science

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