(a) A sample of a radioactive isotope contains N nuclei at time t. At time (t + At), it contains(N-AN) nuclei of the isotope.For the period At, state, in terms of N, AN and At,(i) the mean activity of the sample,activity =(ii) the probability of decay of a nucleus.probability =[1][1](b) A cobalt-60 source having a half-life of 5.27 years is calibrated and found to have anactivity of 3.50 x 105 Bq. The uncertainty in the calibration is +2%.Calculate the length of time, in days, after the calibration has been made, for the statedactivity of 3.50 x 105 Bq to have a maximum possible error of 10%.

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(a) A sample of a radioactive isotope contains N nuclei at time t. At time (t + At), it contains (N-AN) nuclei of the isotope. For the period At, state, in terms of N, AN and At, (i) the mean activity of the sample, activity = [1] (ii) the probability of decay of a nucleus. probability = [1] (b) A cobalt-60 source having a half-life of 5.27 years is calibrated and found to have an activity of 3.50 x 105 Bq. The uncertainty in the calibration is +2%. Calculate the length of time, in days, after the calibration has been made, for the stated activity of 3.50 x 105 Bq to have a maximum possible error of 10%.

(a) A sample of a radioactive isotope contains N nuclei at time t. At time (t + At), it contains (N-AN) nuclei of the isotope. For the period At, state, in terms of N, AN and At, (i) the mean activity of the sample, activity = [1] (ii) the probability of decay of a nucleus. probability = [1] (b) A cobalt-60 source having a half-life of 5.27 years is calibrated and found to have an activity of 3.50 x 105 Bq. The uncertainty in the calibration is +2%. Calculate the length of time, in days, after the calibration has been made, for the stated activity of 3.50 x 105 Bq to have a maximum possible error of 10%.