Answer:

Step-by-step explanation:
Quadratic function is given as 
Let's find a, b and c:
Substituting (0, 6):



Now that we know the value of c, let's derive 2 system of equations we would use to solve for a and b simultaneously as follows.
Substituting (2, 16), and c = 6








=> (Equation 1)
Substituting (3, 33), and c = 6








=> (Equation 2)
Subtract equation 1 from equation 2 to solve simultaneously for a and b.


Replace a with 4 in equation 2.
The quadratic function that represents the given 3 points would be as follows:



The total charge would be $445.
Hope this helps!!
Answer:
(13+83+85+87+90+91+93+97+98+99+100+100):12= 85,33
First, we convert it into a unit like this
20 workers × 30 days = 600 units work
After leaving the 5 workers, we have 35 days to complete the work.
In 35 days only 15 workers will do the work.
So the work completed in 35 days by 15 workers = 35 ×15 =525 units
Remaining unit = 600 -525 =75 units
This unit would do by 5 workers in (75/5) = 15 days.
So after 15 days, 5 workers should leave the job.