These tables represents a quadratic function with a vertex at (0,3) what is the average rate of change for the interval from x=8
to x=9
1 answer:
There are a few ways to do it; the easiest is just to follow the pattern of taking away two from the average.
The next lines of the table are
6 to 7 -13
7 to 8 -15
8 to 9 -17
Answer: C. -17
Let's find the equation and do it that way.
We have a vertex at (0,3) so we can fill out the vertex form a bit. In general for vertex (p,q) it's
y = a(x-p)^2+q
We have
f(x) = ax^2 + 3
f(1) = 2
a+3 =2
a = -1
So we found our equation,
y = -x^2 + 3
Let's check it at x=5, y=-5^2+3=-25+3=-22, good
We want the rate of change from 8 to 9, which is
Answer: -17 again, that checks
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Answer:
The reason why standard deviation of the entire class is greater than standard deviation of males and females considered separately, is that mean values for males and females are different from each other.
Step-by-step explanation:
The concept of mean is well represented by the following formula
mean = , where x1, x2, xn are the observations and N is the number of observations (population).
Standard deviation represents the distance between each observation and the mean of the population (all observations). The formula for this parameter is:
Standard deviation =√[((x1 - x)² + (x2-x)² + ....+ (xn-x)²)/N-1], where x1, x2,..., xn are the observations and x is the mean value.
In this case you have that each height registered is an observation and the number of observations represents the N value. As you can see if the mean for males is different from that of females their standard deviation will be different too. Usually males have heigths greater than that of females (1.77 vs 1.64, in USA for example), and heights inside each group will be more similar than between groups. Then, when you mix all observation there will be an increase in standard deviation, because you are mixing very different heigths