The rate of change of the risk of down syndrome (in percentage of births per year) is
r(x) = 0.004641x² - 0.3012x + 4.9, 20≤ x ≤ 45
where
x = maternal age at delivery.
The function giving risk as a percentage of births when maternal age is x is the integral of r(x). That is,
f(x) = 0.001547x³ - 0.1506x² +4.9x + c
When x = 30, f = 0.14%. Therefore
0.001547(30³) - 0.1506(30²) + 4.9(30) + c = 0.14
41.769 - 135.54 + 147 + c = 0.14
c = -53.089
Answer:
f(x) = 0.001547x³ - 0.1506x² + 4.9x - 53.089, 20 ≤ x ≤ 45
The function is graphed as shown below.
