[填空题]
The mass of a radioac) 7o+-1dkzjkra;mb0k kneo4 k5 wv -yjts/ l gwv(( nc02mx2eytive sample is given by
M(t)=P+$Q(\frac{1}{2})^{\frac{t}{300}}$,t≥0 days.where t is the number of days after the sample was collected and measured.
The initial weight of the sample is 20 g. When each atom emits its α-particle, the mass of the atom is reduced by 3.2%.
1.(1)Explain why P is the final mass of the sample after every atom in the sample has emitted its α-particle.
(2)Hence, find the value of P, leaving your answer correct to two decimal places. P ≈ g
2.Find the value of Q. Q =
3.Estimate the mass of the sample after 2.5 years (assume no leap years). M ≈ g
