31. Heights of Females The mean height of an adult female in New York City is estimated to be 63.4 inches with a standard
deviation of 3.2 inches. What proportion of the adult females in
New York City are
(a) less than 63.4 inches tall?
(b) between 63 and 65 inches tall?
(c) taller than 6 feet?
(d) exactly 5 feet tall?

let's call the solutions x₁ = (5 - 2√7)/3 and x₂ = (5 + 2√7)/3

then the equation is (x-x₁)(x-x₂) = 0

if you fill that in you get a lot of numbers which you can recognize as ax²+bx+c=0.

step-by-step explanation:

you can see that a=1 (there is just an x²)

b = (-5 -2√7 + 2√7 - 5)/3 = -10/3

c = -2√7)/3 ) * (-5+2√7)/3) = -1/3

so your answer is 3x^2 – 10x – 1 = 0