This kind of sampling is called the Cluster sampling. The cluster sampling method is done by dividing the population by groups called clusters. There will be an equal number of samples drawn from each cluster using simple random sampling. In here, the population are the students which are divided into clusters - by year level. 15 students will be selected from each cluster.
What kind of elements like on the periodic table? Please be more specific so I could try to help
well, let's keep in mind that the SAS postulate, so if one Side and the Angle next to it and the following Side after the angle are equal on both triangles, both triangles are congruent. Now, we have the angle 30° with sides and 9 and 2x and sides 9 and x + 4, well, the 9's are equal, dohh, you know, if only the 2x = x + 4, we'd be golden

Answer:
see below
Step-by-step explanation:
Bowling:
15+5x where x is the number of people
Skating:
20+3x
We have 50 dollars so the amount must be less than or equal to 50
Bowling
15+5x≤50
Subtract 15 from each side
15-15+5x≤50-15
5x ≤35
Divide each side by 5
5x/5 ≤35/5
x ≤7
She can have 7 or less people
Skating
We have 50 dollars so the amount must be less than or equal to 50
20+3x ≤50
Subtract 20 from each side
20-20+3x ≤50-20
3x ≤30
Divide each side by 3
3x/3 ≤30/3
x ≤10
She can have up to 10 people
She can invite more people skating
Answer: 64
Step-by-step explanation:
If there are 4 cups in each quart multiply 16 quarts by 4 and you get 64 :)