The characteristic being calculated here is the mean or the average of the data set.
To check:
(20.73 + 20.76 + 20.68 + 20.75)/4 [we divide it by 4 because there are 4 numbers]
= 82.92 / 4
= 20.73
16000
is the answer
because I used the calculater
The half-life of cobalt-60 is 5.26 years. After 10.52 years, 5 grams of a 20-gram sample will remain is TRUE
<u>Explanation:</u>
Mass of cobalt = 20 g
Half-life = 5.26 years
Mass remains after 10.52 years = 5 g
This can be solved by using given below formula, 
= initial mass
t = number of years from when the mass was m_0
m(t) = remaining mass after t years
Number of half-lives = 
Number of half-lives = 
Number of half-lives = 2
At time zero = 20 g
At first half-life = 
= 10 g
At second half life = 
= 5 g
The given statement is true.
Answer : The correct option is 'X' (mitochondria).
Explanation :
In the given animal cell diagram,
W represent the vacuole.
X represent the mitochondria.
Y represent the nucleolus.
Z represent the cytoplasm.
The function of vacuole, it stores waste products and balance the pH level of the cell.
The function of mitochondria, most of the respiration reaction occurs in which carbon dioxide is produced by utilizing oxygen.
The function of nucleolus, it contains the hereditary information.
The function of cytoplasm, most of the chemical reaction occurs.
Therefore, the correct answer is 'X' (mitochondria).
