Chlorofluorocarbons (CFCs) were used as propellants in spray cans until their
build up in the atmosphere started destroying the ozone, which protects us
from ultraviolet rays. since the 1987 Montreal Protocol (an agreement to curb
CFCs), the CFCs in the atmosphere above the US have been reduced from a high
of 3200 parts per trillion (ppt) in 1994 to 2750 ppt in \(2010 .^{15}\) The
reduction has been approximately linear. Let \(C(t)\) be the concentration of
CFCs in ppt in year \(t\)
(a) Find \(C(1994)\) and \(C(2010)\)
(b) Estimate \(C^{\prime}(1994)\) and \(C^{\prime}(2010)\)
(c) Assuming \(C(t)\) is linear, find a formula for \(C(t)\)
(d) When is \(C(t)\) expected to reach 1850 ppt, the level before CFCs were
introduced?
(e) If you were told that in the future, \(C(t)\) would not be exactly linear,
and that \(C^{\prime \prime}(t)>0,\) would your answer to part (d) be too early
or too late?