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
Im gonna asume you mean side, so 1 foot = 12 inches (:
Answer:
A
Step-by-step explanation:
The directrix of the parabola is 
<h3>How to determine the equation of the directrix?</h3>
The parabola equation is given as:

A parabola is represented as:

By comparing both equations, we have:
4p = 1/4 ==> p = 1/16
-k= 3 ==> k = -3
The directrix is represented as:
y = k - p
So, we have:

Take the LCM

Evaluate

Hence, the directrix of the parabola is 
Read more about parabola at:
brainly.com/question/1480401
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