Let C(t) be the total value of US currency (coins and banknotes) in circulation at time. The table gives values of this function from 1980 to 2000, as of September 30, in billions of dollars. Estimate the value of C(1990) .

t 1980 1985 1990 1995 2000
C(t) 129.9 187.3 271.9 409.3 568.6

3 answers

I see that C(1990) is given as 271.9

What are you asking?
I have this question in my homework .its a multiple choice,
Select the correct answer. Answers are in billions of dollars per year.
and the answers are
a)137.4

b)44.4

c)22.2

d)16.96

e)27.48
its asking for C'(1990)