Answer:
a) cluster sampling
Step-by-step explanation:
In cluster sampling method, each member of a population is assigned to one and only one group.This means clusters are formed through probability method usually a simple random sampling.The participants in the clusters are the only one to be surveyed.
In this example, simple random sampling is used to identify 12 home rooms(cluster) where a group of 20 students (participants) in each room is given the survey.
We need to use the variables m and n to represent both numbers.
Their sum must equal -15. Therefore, we can write the next equation:
m + n = -15
If one number is five less than the other, we need to choose one variable and then we can write it in terms of the other variable. Then:
n = m-5
To find the value for each number, we can replace the n equation on the first equation:
m + n = -15
m + (m-5)= -15
Then:
m + m - 5 = -15
2m -5 = -15
Solve the equation for m:
Add both sides 5 units:
2m - 5 +5 = -15+5
2m = -10
Divide both sides by 2:
2m/2 = -10/2
m = -5
Finally, replace the m value on the first equation:
m + n = -15
-5 + n = -15
Then, solve the equation for n:
Add both sides by 5:
-5+5 + n = -15 +5
n = -10
Hence, both numbers are m=-5 and n= -10.
The equations separated by a comma are m + n = -15,n = m-5.
The numbers separated by a comma are -5,-10.
The answer is 520 millimeters
Answer:
D
Step-by-step explanation:
First of all, a very easy way is to count all the rectangles and then count the squares that are shaded and have balloons.
You'll get 7 squares that are shaded and have balloons and 16 rectangles in total.
So the fraction will be 
Another simple way is to just multiply 
and 
