Answer:
18.42 g
Step-by-step explanation:
Using the exponential growth / Decay function :
A = Pe^kt
A = final amount ; P = initial amount, t = number of years ; t = 20
A = 30e^-(0.0244 * 20)
A = 30e^-0.488
A = 30 * 0.6138528
A = 18.415586
Strontium present after 20 years will be :
18.42 g
