Precalculus
posted by Miguel .
The burial cloth of an Egyptian mummy is estimated to contain 57% of the carbon14 it contained originally. How long ago was the mummy buried? (The halflife of carbon14 is 5730 years.)

solve
.57 = 1(1/2)^(t/5730)
log both sides
log .57 = log (.5)^(t/5730)
log .57 = t/5730 (log .5)
t/5730 = log .57/log .5
t/5730 = .810966
t = 4646.8
appr. 4647 years