Answer :
Answer:
A. about 3.4 seconds
Step-by-step explanation:
Given the volume of air in liters in the human lungs described by the function V(t) = 0.173t +0.15t^2 - 0.035t^3 where t is the time in seconds,
The beginning of this respiratory cycle for the lungs to fill to their maximum volume of air occurs when dV/dt = 0
dV/dt = 0.173 + 0.3t - 3(0.035)t²
dV/dt = 0.173 + 0.3t - 0.105t²
Since dV/dt = 0
0.173 + 0.3t - 0.105t² = 0
multiply through by -1
-0.173 - 0.3t + 0.105t² = 0
0.105t² -0.3t-0.173 = 0
Factorize;
t = 0.3±√0.3²+4(0.105(0.173))/2(0.105)
t = 0.3±√0.09+0.07266/0.21
t = 0.3±√0.16266/0.21
t = 0.30±0.4033/0.21
t = 0.7033/0.21
t = 3.349secs
t ≈ 3.4secs
Hence it will take about 3.4secs for the lungs to fill to their maximum volume of air