At a party there are 30 students over the age of 18 and 20 students under 18. You

randomly choose 3 students over 18 and 2

students under 18 to interview. This is an

example of:

A. A convenience sample

B. A self-selected sample

C. A systematic sample

D. A random sample

First locate the turning point (vertex) of the graph. which is at the coordinates x=5 and y=9 or (5; 9).to determine whether it's a maximum or mininum value, you have to discern whether the vertex's y-value is the highest value or lowest value the graph can reach. since the vertex's y-value, 9 is the highest value the graph can reach, it will be a maximum.another basic way to determine whether the vertex's value is max or min is to see if the graph is smiling or sad. if it's smiling, the turning point/vertex would be a minimum, while a sad parabola would have a maximum y-value at the vertex.