Mathematics
Grade 7
15 min
Half-life and population doubling
Half-life and population doubling
Tutorial Preview
1
An element has a half-life of 10 years. If you start with 80g, how much is left after 20 years?
2
A bacteria colony starts with 5 cells and doubles every hour. How many cells are there after 3 hours?
3
A fossil has 25g of a substance with a half-life of 5,000 years. How much was there 10,000 years ago?
Sample Practice Questions
Easy
A sample of 20g of a substance has a half-life of 1 day. How much is left after 1 day?
0.10g
1.20g
2.5g
3.40g
Easy
A population of 10 cells doubles every hour. How many cells are there after 1 hour?
0.15
1.20
2.10
3.5
Easy
A radioactive material weighs 80mg. Its half-life is 1 year. How much is left after 2 years?
0.40mg
1.30mg
2.20mg
3.10mg
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