In 2015, the mean SAT critical reading score for college-bound seniors was 495, with a standard deviation of 116. What is the z
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The true statement about the directrix is that each directrix of this ellipse is 31.25 units from the center on the major axis.
<h3>How to determine the distance of the directrix?</h3>The equation of the ellipse is given as:
The above means that:
a^2 = 625
a = 25
b^2 = 225
b = 15
Calculate c using:
c^2 = a^2 - b^2
This gives
c^2 = 625 - 225
Evaluate the difference
c^2 = 400
Evaluate the square root
c = 20
The equation of the directrix is
x - x₀ = ± a²/c
So, we have:
x - x₀ = ± 625/20
Evaluate the quotient
x - x₀ = ± 31.25
This means that, each directrix is 31.25 units from the center on the major axis.
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