Answer: 74.919 grams
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Step-by-step explanation:
One half-life formula we can use is
y = P*(0.5)^(x/H)
where,
- x = number of years = 160
- y = amount present after x years = unknown for now
- H = half-life = 1690 years
- P = starting amount = 80 grams
So,
y = P*(0.5)^(x/H)
y = 80*(0.5)^(160/1690)
y = 74.9186780773447
y = 74.919
There are roughly 74.919 grams of radium leftover.