Answer:
i.e. 393650 kg.
Step-by-step explanation:
Given that Radium-226 is a radioactive substance with an annual decay rate of 0.04 %
Let the year 1937 be 0 year
Initially population was = 400,000 kg
Since decay rate is 0.04% per year after t years population would be
[tex]P(t) = 400,000 (1-0.0004)^t[/tex]
=[tex]400,000*0.9996^t[/tex]
In 2017, t = 40 years (i.e. years lapsed form 1937)
Hence population
= [tex]P(40) = 400,000 (0.9996)^{40} \\=393649.66[/tex]
i.e. 393650 kg.