math
posted by Jackie on .
An innovative rural public health program is reducing infant mortality in a certain West African country. Pretend the program in Senegal has been reducing infant mortality at a rate 8.1 % per year. How long will it take for infant mortality to be reduced by 30 %?

100  8.1 = 91.9
so each year number = .919 of year before
how many years before amount = 0.7 * original?
.7 = .919^n
log .7 = n log .919
.1549 = n (.03668)
n = 4.22 years