An equation for the parabola would be y²=-19x.
Since we have x=4.75 for the directrix, this tells us that the parabola's axis of symmetry runs parallel to the x-axis. This means we will use the standard form
(y-k)²=4p(x-h), where (h, k) is the vertex, (h+p, k) is the focus and x=h-p is the directrix.
Beginning with the directrix:
x=h-p=4.75
h-p=4.75
Since the vertex is at (0, 0), this means h=0 and k=0:
0-p=4.75
-p=4.75
p=-4.75
Substituting this into the standard form as well as our values for h and k we have:
(y-0)²=4(-4.75)(x-0)
y²=-19x
A = B
6.9 => 7 8.3 => 8
8+7=15
6.2 => 6 8.5 => 9
6+9=15
so A = B
Using the percentile concept, it is found that 10 students scored lower than he did.
<h3>What is the meaning of the percentile of a measure?</h3>
When a measure is in the xth percentile of a data-set, it is greater than x% of the measures and lesser than (100 - x)%.
In this problem, he scored on the 20th percentile, that is, higher than 20% of the 50 students. Then:
0.2 x 50 = 10.
10 students scored lower than he did.
More can be learned about percentiles at brainly.com/question/24495213
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Answer:
-232
Step-by-step explanation:
the salt flats have an elevation of 50 feet greater than -282, so add 50 to -282 and you get -232
