As online attacks persist, spending on information security software continues to rise. The following table gives the forecast for the worldwide sales (in billions of dollars) of information security software through 2007 (x = 0 corresponds to 2002).

y = 10^9 (6.87 + 2.1(year-2002) )

Step-by-step explanation:

y = a + b x

x mean = 15/6 = 2.5

y mean = 72.7/6 = 12.12

x-x mean

-2.5 -1.5 -.5 +.5 +1.5 + 2.5

y - y mean

-6.12 -3.22 -.22 +1.88 +3.58 +4.08

(x - x mean)(y - y mean)

15.3 4.83 .11 .94 5.37 10.2

sum of those = 36.75

(x - x mean)^2

6.25 2.25 .25 .25 2.25 6.25

sum of those = 17.5

so

b = 36.75/17.5 = 2.1 agree with you

a = y mean - b x mean

= 12.12 - 2.1* 2.5 = 6.87 agree with you

y = 6.87 + 2.1 t

perhaps you used x in last line instead of t?

or

perhaps they want real years and billions

y = 10^9 (6.87 + 2.1(year-2002) )

a. turk and mcalister

b. howard, mission, and market

c. yes. since streets end some do not cross yet are not parallel to others. example: mcalister and 5th

step-by-step explanation:

parallel lines are lines which do not intersect ever and look a lot like railroad tracks. turk, mcalister and golden gate are examples of these.

intersect are streets which cross each other and a car on one can reach the other. howard, mission, and market intersect with 6th.

skew lines are lines which neither intersect nor are parallel. these lines exist here because some streets end and never intersect another like mcalister and 5th.