A sample contains 30 MBq of 210-Pb (half-life time : 22 yr) and 15 MBq of 210-Bi (half-life tiem : 5 d) at time t = 0. (a) Calculate the activity of 210-Bi at time t = 10 days. (b) If the sample ori

A sample contains 30 MBq of 210-Pb (half-life time : 22 yr) and 15 MBq of 210-Bi (half-life tiem : 5 d) at time t = 0.

(a) Calculate the activity of 210-Bi at time t = 10 days.

(b) If the sample originally pure 210-Pb, then how old is it at the time t = 0.