TMSCA #6

[calcguy]

Here is a correction on 09C-27. "An insect population triples every 25 days. If an insecticide kills 70% of the insects, how often should it be applied to keep the insect population in check?"
The correct answer is 27.4 days. Solution: y = y0 x b^(t/T) where y is final amount, y0 is initial amount, b is base, t is time from y0 to y, and T is time for y0 to be multiplied by b.
Like this: 1/0.3 = 1 x 3^(t/25); t = 25 x ln(1/0.3)/ln(3) = 27.4 days

[88bobcat]