Question 1132025
P-ab^x
at time 0, 60000=a*b^0
a is 60000
at time 15 (years after 1980)
80000=60000*b^15
4/3=b^15
take the 15th root of 4/3
b=1.01936
500000=60000*1.01936^x
8.3333=1.01936^x
ln both sides
ln 8.3333=x ln 1.01936
x=ln 8.3333/ln 1.01936
=110.57 years or in mid 2091.