Question

10. The S-Cargo shipping company calculates shipping charges using the linear model, y = 2.72x, where y is the cost in dollars and x is the weight of the package in pounds (1 ≤ x ≤ 9). Use the linear model to compute the weight of a package with a shipping cost of $21.76. Round to the nearest hundredth of a pound, if necessary.

11. Two cars are 270 miles apart and travel toward each other on the same road. They meet in 3 hours. One car travels 2 mph faster than the other. What's the average speed of each car?

12. A line contains the point (4, 5) and is perpendicular to a line with a slope of . Write an equation of the line satisfying the given conditions. Write the answer in slope-intercept form.

13. Solve the equation: 6 – 3(–2 – 4x) = 2(3(x – 4) + 7)

14. A freight train and a passenger train leave a rail yard at the same time and travel on parallel tracks. The passenger train travels 6 mph faster than the freight train. The combined distance traveled after 2 hours is 100 miles. What's the average speed of each train?

Answer 1

10) a) y = 2.72 x

When y = 21.76, x =21.76/2.72 = 8 pounds

11) Let speed of one car be x.  Then speed of other car=x+2 and relative velocity = x+x+2 =2x+2

Distance /time = speed :  i.e. 2x+2=270/3 =90:

i.e. 2x+2 =90

x=44 mph

Answers are 44 mph and 46 mph.

12) Slope of perpendicular line not given

13) 6-3(-2-4x) = 2(3(x-4)+7)

6+6+12x = 2(3x-12+7)

12+12x =6x-10

6x =-22

x= -11/6

14) Let speed be x and x+6.  

Combined distance after 2 hours = 2x+2(x+6) = 100

x+x+6 =50

x = 22 .  So answers are 22 and 28 mph.