Answer:
k = -2
Step-by-step explanation:
f(x) = (x − h)² + k
(h, k) is the (x, y) coordinate of the vertex
For a vertex of (4, -2)
h = 4
k = -2
Ratio of classes A, B, C = 4 : 6 : 5, respectively
4 + 6 + 5 = 15
So, class A represents 4/15 of the TOTAL population
Class B represents 6/15 of the TOTAL population
Class C represents 5/15 of the TOTAL population
So, weighted average of 3 groups combined = (4/15)(65) + (6/15)(80) + (5/15)(77)
= 260/15 + 480/15 + 385/15
= 1125/15
= 75
Answer: B