Answer:
$17.750 ; 15.979 ; 72
Step-by-step explanation:
Given that :
Cummulative sales, S(t) is represented by the equation :
S(t) = 72/(1 + 9e^-0.36t)
Cummulative sales after 3 weeks :
Put t = 3 in the equation, as t = time after launch
S(3) = 72/(1 + 9e^-0.36(3))
S(3) = 72 / (1 + 9e^-1.08)
S(3) = 72 / (1 +3.0563597)
S(3) = 72 / 4.0563597
S(3) = 17.749905 = $17.750 thousands
Amount of time required for sales to reach 70000
S(t) = 72/(1 + 9e^-0.36t)
S(t) = 70
70 = 72/(1 + 9e^-0.36t)
70 * (1 + 9e^-0.36t) = 72
(1 + 9e^-0.36t) = 72 / 70
1 + 9e^-0.36t = 1.0285714
9e^-0.36t = 1.0285714 - 1
9e^-0.36t = 0.0285714
e^-0.36t = 0.0285714 / 9
e^-0.36t = 0.0031746
Take the In of both sides ;
In(e^-0.36t) = In(0.0031746)
-0.36t = - 5.752573
t = - 5.752573 / - 0.36
t = 15.979
About 16 weeks
The limiting value in sales :
Take the limit as t - - > ∞
S(t - - > ∞) = 72/(1 + 9e^-0.36t)
Put t = 0
S(0) - - > 72 / (1 + 0)
72 / 1
= 72
