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) )

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

answer: 4 (:

step-by-step explanation: