A telephone company charges a fixed monthly rate plus a rate per minute of usage. The company charges $120 for 100 minutes of usage and $95 for 50 minutes of usage. An equation can be written to show the relationship between the total minutes used (x) and the total monthly charges (y). Which of the following best describes the steps to draw the graph of y against x?

Question

anonymous · Answer

Draw a graph which joins the points (100, 120) and (50, 95) and has a slope = 0.50

Draw a graph which joins the points (100, 120) and (50, 95) and has a slope = 2

Draw a graph which joins the points (120, 100) and (95, 50) and has a slope = 2

Draw a graph which joins the points (120, 100) and (95, 50) and has a slope = 0.50

anonymous · Answer

Sorry just a sec lol

anonymous · Answer

Lol its good

anonymous · Answer

Okay

anonymous · Answer

So it looks like it all comes down to what the slope should be and which way the ordered pairs should be.

anonymous · Answer

Since x is total money and y is total months either C or D is correct.

anonymous · Answer

Wait those are minutes not months

anonymous · Answer

Oh actually it's easier than that

anonymous · Answer

we just have to get the slope of the 2 points

anonymous · Answer

Okay.

anonymous · Answer

But it seems that x is for minutes and y is for money

anonymous · Answer

I forgot that formula..

anonymous · Answer

"The company charges $120 for 100 minutes" would be (100, 120)

anonymous · Answer

Okay

anonymous · Answer

The other point would be (50, 95)

anonymous · Answer

So we need the slope of those two points: (50, 95) and (100, 120)

anonymous · Answer

Yes. But thats what I forgot

anonymous · Answer

$$slope = \frac{ y }{ x } = \frac{ rise }{ run } = \frac{ y2 - y1 }{ x2 - x1 }$$

anonymous · Answer

Ah-ha!

anonymous · Answer

So in this case $$\frac{ 120 - 95 }{ 100-50 }$$

anonymous · Answer

So now we just need this simplified

anonymous · Answer

thats 1/2

anonymous · Answer

So the slope is 1/2, or 0.5 in the answers

anonymous · Answer

And as for the ordered pairs, it was (100, 120) and (50, 95) instead of the other way around because x was minutes and y was time, again instead of the other way around.

anonymous · Answer

The way they worded would have made it seem like it was as it was read.

anonymous · Answer

So which answer would you choose

anonymous · Answer

A.

anonymous · Answer

Same here :)

anonymous · Answer

Thank you! you're a lot of help!

anonymous · Answer

No prob lol