9514 1404 393
Answer:
-0.16
Step-by-step explanation:
The 'a' value can be found by looking at the difference between the y-value of a point 1 unit from the vertex, and the y-value of the vertex.
Here, that is a negative fraction of a unit. If we assume the value is a rational number that can be accurately determined from this graph, then we can find it by looking for a point where the graph crosses a grid intersection. It looks like such grid points are (-7, 0) and (3, 0). The vertex is apparently (-2, 4), so the vertex form of the equation is ...
y = a(x +2)^2 +4
Using the point (3, 0), we have ...
0 = a(3 +2)^2 +4 . . . . . fill in the values of x and y
-4 = 25a . . . . . . . . . . subtract 4; next, divide by 25
a = -4/25 = -0.16
Tammy's sample may not be considered valid because, on the first hand, it is said that she only asked students from her " Math Class".
If she wants to have a survey to find out the favorite subject of the students at her school, she must conduct a survey involving all the students in her school, not just in her class. What she did is just subjective. She should use a tally listing the different subjects and compare the number of students per subject. This way, she can have an objective representation of the least liked subjects and the most liked subjects of the students on her school.
Illustrating her survey through statistics may be more reliable and valid because it shows frequencies in which she can calculate easily and accurately the percentage of the number of students per subject, in a more objective manner.
The unit rate is 5/1
15/3=5
3/3=1
Based on the information given, the number of tokens that will be bought if a child has $20 will be 70.
Since a child can buy 21 tokens for $6, the cost of one token will be:
= $6 / 21 = $0.2857143
Therefore, if a child has $20, the number of tokens that will be gotten will be:
= $20 / $0.2857143
= 70
Therefore, 70 tokens will be bought.
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