Using an exponential function, it is found that it takes 18.6 days for 80% of the material to decay.
The amount of a substance after t days is modeled by:

In which:
- k is the decay rate, as a decimal.
- A(0) is the initial amount.
The half-life is of 8 days, hence
, and this is used to find k.







Hence:

The time it takes for 80% of the material to decay it t for which
, hence:






It takes 18.6 days for 80% of the material to decay.
To learn more about exponential functions, you can take a look at brainly.com/question/24906920
9x mean 9 multipled with an unkown number and 9x is subtracted from another unknown number 'y' . you can substitute with any letters you want ,but you have to use two different letters.
The answer is 1/2 due to the slope
Answer:
$48.60
Step-by-step explanation:
First multiply the amount due by the tax
45 x .08 = 3.6
Final step add the tax to the amount due
45 + 3.6 = 48.6
Answer:
A systematic sample
Step-by-step explanation:
since there is an increasing trend in the unpaid balances because of the rising cost of housing the best approach is A systematic sample.
A systematic sample is preferred because it will capture the individual debts over the period of 20 years (i.e. the whole 20 years of mortgages ) while a simple random sample will just capture a certain period and its result will not represent the true nature of indebtedness .