The nuclide I  131 is radioactive, with a half-life of 8.04 days. At noon on January 1, the activity of a certain sample is 600Bq. The activity at noon on January 24 will be

Number of days from january 1st to january 24th = 23 days.Number of half lives n=238.04=2.86(<3)In three half lives activity becomes 75 Bq, but the given number of half lives are lesser than 3 so activity becomes greater than 75 Bq.