Answer:
c
Step-by-step explanation:
Let 
be the random variable for the number of marks a given student receives on the exam.
10% of students obtain more than 75 marks, so
where 
follows a standard normal distribution. The critical value for an upper-tail probability of 10% is
where 
denotes the CDF of , and 
denotes the inverse CDF. We have
Similarly, because 20% of students obtain less than 40 marks, we have
so that
Then 
are such that
and we find
The equation of a hyperbola is:
(x – h)^2 / a^2 - (y – k)^2 / b^2 = 1
So what we have to do is to look for the values of the variables:
<span>For the given hyperbola : center (h, k) = (0, 0)
a = 3(distance from center to vertices)
a^2 = 9</span>
<span>
c = 7 (distance from center to vertices; given from the foci)
c^2 = 49</span>
<span>By the hypotenuse formula:
c^2 = a^2 + b^2
b^2 = c^2 - a^2 </span>
<span>b^2 = 49 – 9</span>
<span>b^2 = 40
</span>
Therefore the equation of the hyperbola is:
<span>(x^2 / 9) – (y^2 / 40) = 1</span>
Answer:
Step-by-step explanation:
13-16y is the same as -16y+13.
