Answer:
Step-by-step explanation:
The centerpoint (a,b) is (6,7), the radius r is 2. Both can be read from the graph.
With that you can fill in the standard equation of a circle:
We'll say beginning amount is 100
Ending Amount = Beginning Amount / 2^n where n is the number of half-lives
100 hours mean six and 2/3 half-lives will elapse
Ending Amount = 100/2^(6.666666)
Ending Amount = 100 /
<span>
<span>
<span>
101.59
</span></span></span>Ending Amount =
<span>
<span>
<span>
0.9843488532
</span>
</span>
</span>
So if we started with 100 grams after 100 hours (or 6.6666666 half-lives) we would only have <span>
<span>
0.9843488532
</span>
grams remaining.
http://www.1728.org/halflife.htm
</span>
First, we need to find her current age. If she was 12 years old 3 years ago, her current age is 12 + 3 which is 15. If the ratio of Sarah's age to Keisha's age is 4:5 (Sarah's age is the 4 and Keisha's age is the 5).
If we take 15 and divide that by 5 (her ratio), then you get 3. Now multiply 3 by 4 to find Sarah's age. We get 12. Nine years from now, her age is 12 + 9 which is 21.
There is the answer. Sarah's age in 9 years is 21 years old. I hope this helps.
