Annual retail store revenue for a technology company from 2007 to 2017 are shown below.

Year	Period	Retail Store Revenue ($ billions)
2007	1	3.915
2008	2	6.110
2009	3	6.777
2010	4	8.880
2011	5	14.327
2012	6	19.028
2013	7	20.428
2014	8	21.262
2015	9	27.909
2016	10	26.998
2017	11	30.703

(b)

Using statistical software, develop a linear trend equation for this time series to forecast revenue (in $ billions). (Round your numerical values to four decimal places.)

T_t =______

(c)

Use the trend equation developed in part (b) to forecast retail store revenue (in $ billions) for 2018. (Round your answer to one decimal place.)

$ billion ____