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The half-life ('HWZ') of a [translation unavailable] of which: 10 years. After how many years (expressed as 'full multiples of the HWZ') the following quantity has been obtained from the original number of atoms
- half
- a quarter
- a 128th
- about 1 per cent
- Approximately 1 promille
- About a millionth
Hinweis: Firstly question not at all: how many half-lives are past?
Solution: - Half: one HWZ has expired, so 10 years
- A quarter: [translation unavailable] two HWZ, thus 20 years
- A 128th: [translation unavailable] seven HWZ, thus 70 years
- Approx. 1 percentage: thus approx. A one-hundredth. 1/64 would be 6 HWZ, 1/128 would be 7 HWZ, thus between 60 – 70 years
- Approx. 1 prometheus: thus approx. A one thousandth. 9 HWZ (=1/512), 10 HWZ (1/1024), thus between 90 – 100 years
- Approx. A one millionth: 2x=1'000'000, x between 19 and 20. Thus thus 190 – 200 years. Exercise can also without mathematics dissolved are, on the pocket calculators 2x try it, to greater as a [translation unavailable].
With mathematics: 2x =1'000'000, x = log(1'000'000)/log(2) = 19.93
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