Answer: 307.7 grams
Step-by-step explanation:
The exponential decay equation with initial value 'A' and rate of decay 'r' ( in decimal) in 't' years is given by :-
[tex]M(t)=A(1-r)^t\quad...(i)[/tex]
As per given , we have
Initial mass of isotope = 1500 grams
Rate of decay : r= 8% =0.08
To find : the mass of the radioactive sample at the beginning of the 20th day of the experiment ( i.e. after 19 days).
That would be ,
[tex]M(19)=1500(1-0.08)^{19}[/tex] [Using (i)]
[tex]M(19)=307.652167113\approx307.7[/tex] [Rounded to the nearest tenth]
Hence, the mass of the radioactive sample at the beginning of the 20th day of the experiment = 307.7 grams
