(Please explain how you solved this, need help)
the percentage of US households with a plasma television set is given by the formula P(t)=(79)/(1+317e^(-.06t)),
where t is measured in years since 2000. according to the formula, the first. year in which at least 75% of all US households will own a plasma television set is
(a) 2009
(b) 2011
(c) 2013
(d) 2015
(e) 2017
so solve
(79)/(1+317e^(-.06t)) = 75