For a long-distance phone call, a hotel charges $9.99 for the first minute and $0.79 for each additional minute or fraction thereof. A formula for the cost is given by

C(t) = 9.99 − 0.79[[1 − t]], t > 0

where t is the time in minutes.

For example, [[3.2]] = 3 and [[−1.6]] = −2.)

(a) Evaluate C(10.75). What does C(10.75) represent?

(b) Use a graphing utility to graph the cost function for 0 < t ≤ 6. Does the limit of C(t) as t approaches 3 exist? Explain.