Answer:
The prevalence of serious defects in this population at the time of birth is 10%.
Step-by-step explanation:
The prevalence of serious defects is the number of infants that were born with seriours birth defects divided by the total number of infants born.
In this problem, we have that:
There were 1000 newborn infants.
100 infants were born with serious birth defects.
Calculate the prevalence of serious defects in this population at the time of birth.
This is:

The prevalence of serious defects in this population at the time of birth is 10%.
Your answer should be 12.57
The 'x' in x^2-7x-30=0 is 4.
That is called the dependent variable. It depends upon the value of the independent variable.
f(x)=y
So we can see by inspection that the dependent variable y value depends upon the input value of the independent variable x
Any questions please feel free to ask. Thanks
Answer:
It depends, Y or X have to be set up to get an actual number because you can simply plug any numbers.