Question

Due by tomorrow and i have no idea how to do it

Answer 1

okay so your x and y values go where the bold black lines are on the graph. the bottom left hand corner is left clear as it is for the zero value. you plot the numbers given in the table so that each number has it's own line on the graph

then you plot the numbers given in the table by going along the corridor and up the stairs. you essentially find the spot where both x and y values are satisfied. If you don't understand this I can help you further. you then join these plotted points with a line

for the second question, you find the gradient of the line which is the vertical length of the line divided by the horizontal length of the line.

for 3 you find 15 minutes on the x-axis and see where it meets the y-axis on the line that you have plotted

you do the opposite for 4. you find €1.52 on the y-axis and see where it meets on the x-axis on the line that you have plotted

if you have any further questions don't be afraid to ask! I'm very bad at explaining :)

Answer 2

(1) See figure attached

(2) y = 0.12*x + 0.2

(3) $2

(4) 11 minutes

Explanation:

(1)

To make the graph, plot point by point and connect them with a line.

(2)

To get a line's equation you need its slope (m) and its y-intercept (b), because equation form is y = m*x + b.

Knowing 2 points of the line, (x1, y1) and (x2, y2), slope is computed as

m = (y2 -y1)/(x2 - x1)

Replacing with (1, 0.32) (2, 0.44) it gives

m = (0.44 - 0.32)/(2 - 1)

m = 0.12

Know you have the slope, you can get b substituting 1 point in the general equation. Using point (1, 0.32) gives

0.32 = 0.12*1 + b.

b = 0.32 - 0.12*1

b = 0.2

So, the equation is y = 0.12*x + 0.2

(3)

Equation gotten in the previous part of the exercise relate y (cost of the call) with x (number of minutes). So, if you replace x = 15 minutes, then you will get call cost in $.

y = 0.12*15 + 0.2

y = 2

(4)

In an analogous way as before, you have to replace y = $1.52 and isolate x (which is in minutes).

1.52 = 0.12*x + 0.2

0.12*x = 1.52 - 0.2

x = 1.32/0.12

x = 11