Question 33657
L(t)=500[1-e^(-0.006t)]
L(30)=500[1-e^(-0.006(30)]
     =500[0.164729789)
     =82 words
300=500[1-e^(-0.006t)
0.6=[1-e^(-0.006t)
e^(-0.006t)=0.4
Take the natural log of both sides to get:
-0.006t=ln0.4=0.91629...
t=152.72 minutes
Cheers,
Stan H.