Given that the directrix is at y = 4 and the focus is at (0, -4), then the vertex is at (h, k) = (0, 0).
p is the distance between the vertex and the focus and between the vertex and the directrix = 4 and since the focus is below the directrix, p is negative, i.e. p = -4
Equation of a parabola is given by (x - h)^2 = 4p(y - k)
Therefore, the required equation is (x - 0)^2 = 4(-4)(y - 0)
x^2 = -16y
y = -1/16 x^2
Using Chebyshev's Theorem, considering a standard deviation of 40, we have that at least 75% of the students scored between 360 and 520.
<h3>What does Chebyshev’s Theorem state?</h3>
When we have no information about the population distribution, Chebyshev's Theorem is used. It states that:
- At least 75% of the measures are within 2 standard deviations of the mean.
- At least 89% of the measures are within 3 standard deviations of the mean.
- An in general terms, the percentage of measures within k standard deviations of the mean is given by
.
In this problem, considering a standard deviation of 40, we have that:
440 - 2 x 40 = 360.
440 + 2 x 30 = 520.
Within 2 standard deviations of the mean, no information about the distribution, hence, at least 75% of the students scored between 360 and 520.
More can be learned about Chebyshev's Theorem at brainly.com/question/25303620
5x3=15. 15+6=21. The answer would be 3
Answer:
DAM BROOOOO UR SCREEN.
Step-by-step explanation: