In 2011 online sales were 192 billion and in 2015 they are p

In 2011 online sales were $192 billion and in 2015 they are predicted to be $260 billion.

a) Find a linear function S that models these data. Write S(x) in slope intercept form.

b) Interpret the slope of the graph of S.

c) Determine when online sales were $243 billion.

Part a) S(x) = (slope intercept form)

b) Interpret the slope of the graph of S. Choose the correct answer below

a) Sales increased, on average, by $17 billion/yr.

b) Sales increased by $17 billion in next 4 years.

c) Sales decreased by $17 billion in next 4 years.

d) Sales decreased, on average, by $17 billion/yr.

Finally, part c) Online sales were $243 billion in the year ______

2011 online sales were $192 billion and in 2015 they are predicted to be $260 billion.

x =1 in 2011, x =5 in 2015

(1,192),(5,260)

a) linear function

S-192=[(260-192)/(5-1)](x-1)

S-192=17(x-1)

S=17x-17+192

S=17x+175

linear function S that models these data is S(x)=17x +175

a) Sales increased, on average, by $17 billion/yr.

c)S(x)=243

17x +175=243

17x=243-175

x=4

Online sales were $243 billion in the year __2014____