The intensity of light decreases by 4% for each meter that it descends below the surface of the water. At what depth is the intensity of light only 20% of that at the surface?

Answer 1

I = 1 (.96)^m

.20 = .96^m
using logs

m = log .2/log .96 = appr 39.4

it would take about 39.4 m

Answer 2

A colony of bees doubles in population every 5 weeks. how long does it tak for the population to triple?

Answer 3

Log(3/1)/Log(2)=1.58

1.58x5=7.9 weeks