Radium-226 is a radioactive substance with an annual decay rate of 0.04 % . a series of coal mines in poland contain an abundance of the aforementioned isotope of radium. if these coal mines contained 400 thousand kilograms of radium-226 in 1937, then how much radium-226 would be left in those coal mines in 2017? round your answer to the nearest kilogram.

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

=

In 2017, t = 40 years (i.e. years lapsed form 1937)

Hence population

=

i.e. 393650 kg.

d) 30 units^2

area of rectangle = l × b

we know,

length = 10 unit

breadth = 3 unit

applying the formula,

= l × b

= 10 × 3

= 30 unit^2

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