Respuesta :
Half life - when half of the radioactive substance has become stable
500,000/2 = 250,000 remaining after the first half life
250,000/2 = 125,000 remaining after the second
Or alternatively 1/4 x 500,000 = 125,000
500,000/2 = 250,000 remaining after the first half life
250,000/2 = 125,000 remaining after the second
Or alternatively 1/4 x 500,000 = 125,000