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.
R-7=7 add the seven from both sides, leaving the r alone, because this is what you are trying to find. Thus the answer is r=14.
Answer:
option c is correct answer
So if they all add 4 hours to their time then they have:
Jeff 9
Mark 14
Karen 9
Costas 13
Brett 11
Nikki 9
Jack 11
so now to find the mean you add all the numbers together to get 76 and then you divide it by the number of people (7 people) so 76 divided by 7 equals 10.8571429 and that's the mean.
Now to find the median you put all the numbers in order from least to greatest: 9;9;9;11;11;13;14 and you take the number in the middle but since both 11 and 11 are in the middle you take the mean of them and the mean of them is 11 so the median of the numbers is 11
now to find the range you take the largest number (14) and you subtract the smallest number (9) so 14 - 9 is 5 so 5 is the range
and last the mode is the number that is repeated most out of all the numbers so the mode would be 9
