The value of the Conference Board Index of 10 economic indicators in the United States could be approximated by the following function of time t in months since the end of December 2002.

E(t) =

0.2t + 105	if 6 t 15
0.2t + 111	if 15 < t 20.

(a)

Estimate

E(10), E(17), and E(20).

E(10)	=
E(17)	=
E(20)	=

Interpret your answers.

E(10)

means in ---Select--- January February March April May June July August September October November December of the year the Conference Board Index was .

E(17)

means in ---Select--- January February March April May June July August September October November December of the year the Conference Board Index was .

E(20)

means in ---Select--- January February March April May June July August September October November December of the year the Conference Board Index was .

(b)

Sketch the graph of E. Use your graph to estimate when the index first reached 108.

t =

(c)

Use technology to generate a table of values for E(t) with

t = 6, 7, , 20.

t	6	7	8	9	10
E(t)

t	11	12	13	14	15
E(t)

t	16	17	18	19	20
E(t)