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.
Answer:
The number of meters Robert will beat Sam is 12 meters.
Step-by-step explanation:
Given:
When Paul crossed the finish line of a 60-meter race, he was ahead of Robert by 10 meters and ahead of Sam by 20 meters. Suppose Robert and Sam continue to race to the finish line without changing their rates of speed.
Find:
the number of meters by which Robert will beat Sam
Step 1 of 1
When Paul finishes, Robert has run 60-10=50 meters and Sam has run 60-20=40 meters.
Therefore, when Robert and Sam run for the same amount of time, Sam covers 
of the distance that Robert covers. So, while Robert runs the final 10 meters of the race, Sam runs 
meters.
This means Robert's lead over Sam increases by 2 more meters, and he beats Sam by 10+2=12 meters.
Answer: Parallel: y=-2/7x-2 1/7 Perpendicular: y=7/2x+13
Step-by-step explanation:
2x+7y=14
Subtract 2x from both sides.
7y=-2x+14
Divide both sides by 7 to isolate y.
y=-2/7x+2
Parallel:
Plug in x and y with same slope as the original.
-1=-2/7(-4)+b
Solve for b:
-1=8/7+b
-2 1/7=b
y=-2/7x-2 1/7
Perpendicular:
Plug in x and y with the negative inverse of the original slope.
-1=7/2(-4)+b
Solve for b.
-1=-28/2+b
-1=-14+b
13=b
y=7/2x+13
32 and 34? I'm sure that's what the questing is asking. Hopefully that helped. Someone correct me if I'm wrong.
Answer:
perimeter is adding so add all the sides
Step-by-step explanation:
