Problema Solution
The total amount of Visa Credit Card purchases for less than $25 has increased approximately linearly from $14 billion in 2002 to $60 billion in 2006. Let C be the total amount (in billions of dollars) of Visa Credit Card purchases for less than $25 in the year that is t years since 2000. Find an equation of a model C=f(t).
Answer provided by our tutors
f(t) is a linear function thus
f(t) = at + b, where a and b are constants that we need to find
$14 billion in 2002 means
for t = 2002 - 2000 = 2, f(2) = 14 billions of dollars or
a*2 + b = 14
60 billion in 2006 means
for t = 2006 - 2000 = 6, f(6) = 60 billions of dollars or
a*6 + b = 60
by solving the system of equations
a*2 + b = 14
a*6 + b = 60
we find:
a = 23/2
b = -9
click here to see the step by step solution of the system of equations:
f(t) = (23/2)t - 9
the model is C = (23/2)t - 9.