Answer:
174.8 guppies.g/week
Step-by-step explanation:
B(t) = N(t)M(t)
Utilizing the product rule of derivative
[tex]\frac{d(AH)}{dt} = A\frac{dH}{dt} + H\frac{dA}{dt}[/tex]
Applying the rule to B(t) = N(t)M(t)
[tex]\frac{d(B(t))}{dt} = N(t)\frac{d(M(t))}{dt} + M(t)\frac{d(N(t))}{dt}[/tex]
from the question
t=4 weeks, N(4) = 820 guppies
d(N(4))/dt = 50 guppies/week
m(4) = 1.2g
d(M(4))/dt = 0.14g/week
[tex]\frac{d(B(t))}{dt} = N(t)\frac{d(M(t))}{dt} + M(t)\frac{d(N(t))}{dt}\\\\= 820(0.14) + 50 (1.2) = 174.8 guppies.g/week[/tex]