Joongki

This is actually a geometric series problem...which has the formula An=(A1)(r)^(n-1) so substitute the given r=1-1/5 = 4/5 5000 = (25000)(4/5)^(n-1) 5000/25000 = (4/5)^(n-1) 1/5 = (4/5)^(n-1) take ln on both sides ln(1/5) = ln[(4/5)^(n-1)] ln(1/5) = (n-1)...