Answer:
z-score = 2.
Step-by-step explanation:
The z-score = (x - m) / d where x =the person's score, m = the mean and d = the standard deviation.
So we have (87-67)/10
= 2.
Answer:
x = 30
Step-by-step explanation:
Put in proportions 
= 
Cross multiply and get 27x = 45 x 18
OR...
27x = 810.
THEN...
divide by 27 on both sides to get 30
x = 30
Step-by-step explanation:
The equation of a parabola with focus at (h, k) and the directrix y = p is given by the following formula:
(y - k)^2 = 4 * f * (x - h)
In this case, the focus is at the origin (0, 0) and the directrix is the line y = -1.3, so the equation representing the cross section of the reflector is:
y^2 = 4 * f * x
= 4 * (-1.3) * x
= -5.2x
The depth of the reflector is the distance from the vertex to the directrix. In this case, the vertex is at the origin, so the depth is simply the distance from the origin to the line y = -1.3. Since the directrix is a horizontal line, this distance is simply the absolute value of the y-coordinate of the line, which is 1.3 inches. Therefore, the depth of the reflector is approximately 1.3 inches.
S=6a²
a=8mm
S = 6 * 8² = 6 * 64 = 384 mm²
