The new mean age will be greater than 14.2 years because the teacher is older than the previous mean.
Answer:
a = -0.3575
Step-by-step explanation:
The points A and D lie on the x-axis, this means that they are the x-intercepts of the parabola, and therefore we can find their location.
The points A and B are located where

This gives


Now given the coordinates of A, we are in position to find the coordinates of the point B. Point B must have y coordinate of y=2 (because the base of the trapezoid is at y=0), and the x coordinate of B, looking at the figure, must be x coordinate of A plus horizontal distance between A and B, i.e

Thus the coordinates of B are:

Now this point B lies on the parabola, and therefore it must satisfy the equation 
Thus

Therefore


Sec∅ = 1/cos∅
= 1/cos(240)
= 1/cos(180 + 60)
= 1/-cos(60)
= 1/(-1/2)
= -2
Equation of the line:
y=mx+b
Ordinate at the origin (where the line cut the y-axis): b=1
B=(-5,5)=(xb,yb)→xb=-5, yb=5
C=(0,1)=(xc,yc)→xc=0, yc=1
m=(yc-yb)/(xc-xb)
m=(1-5)/(0-(-5))
m=(-4)/(0+5)
m=(-4)/(5)
m=-(4/5)
y=mx+b
y=-(4/5)x+1
Multiplying the equation by 5:
5[y=-(4/5)x+1]
5y=-4x+5
Adding 4x both sides of the equation:
5y+4x=-4x+5+4x
4x+5y=5
Answer: The equation for BC is: Third option 4x+5y=5