Answer:
D. About 800 years
Step-by-step explanation:
Use the half-life equation:
A = A₀ (½)ⁿ
where A is the final amount,
A₀ is the initial amount,
and n is the number of half-lives.
0.90A₀ = A₀ (½)ⁿ
0.90 = (½)ⁿ
To solve for n, take log of both sides:
log 0.9 = n log 0.5
n = (log 0.9) / (log 0.5)
n = 0.152
It takes 0.152 half-lives. The half-life of carbon-14 is 5730 years.
0.152 × 5730 years = 871 years
The closest answer is D.
B. Is the answer because you can fold it in half
I would have to say 85 but thats just a guess.
B is the correct answer.
We are adding the border of x thickness to all 4 sides of the table. This makes the new width of the table 36+x+x = 36+2x and the new length of the table 72+x+x=72+2x. To find the area, we multiply the length and width:
(36+2x)(72+2x) = 3006
Multiplying the binomials, we get:
36*72 + 36*2x + 2x*72 + 2x*2x = 3006
2592 + 72x + 144x + 4x² = 3006
Combining like terms gets us
2592 + 216x + 4x² = 3006
Subtract 3006 from both sides:
2592 + 216x + 4x² - 3006 = 3006 - 3006
-414 + 216x + 4x² = 0
Writing in standard form we have
4x²+216x-414=0
