Answer:
3.17
Step-by-step explanation:
0.45x + 0.72 + 5x = 18
5.45x = 17.28
x = 3.17
A quadratic function is a function of the form

. The
vertex,

of a quadratic function is determined by the formula:

and

; where

is the
x-coordinate of the vertex and

is the
y-coordinate of the vertex. The value of

determines if the <span>
parabola opens upward or downward; if</span>

is positive, the parabola<span> opens upward and the vertex is the
minimum value, but if </span>

is negative <span>the graph opens downward and the vertex is the
maximum value. Since the quadratic function only has one vertex, it </span><span>could not contain both a minimum vertex and a maximum vertex at the same time.</span>
Answer:
a. Fred's margin of error is larger than Ted's.
Step-by-step explanation:
Margin of error of a confidence interval:

In which z is related to the confidence level(the higher the confidence level the larger the value of z)
is the standard deviation of the population and n is the size of the sample.
From this, we have that:
A higher confidence level leads to a larger margin of error.
A larger sample size leads to a smaller margin of error.
In this question:
Same confidence level.
Fred's sample is smaller, so his margin of error will be larger.
The correct answer is given by option a.