Question

A radioactive substance decays with time.

The mass of the substance reduces by
9% each year.
How many years will it take for 800kg of
the substance to decay to a mass of less
than 100kg?

Answer 1

To find the number of years it will take for the radioactive substance to decay from 800 kg to less than 100 kg, we can use the following formula:

100 = 800 * (0.91)^x

where x is the number of years.

Solving for x, we get:

x = log(0.125) / log(0.91)

x ≈ 11.78

So, it will take approximately 11.78 years for the radioactive substance to decay from 800 kg to less than 100 kg.