Question

Total number of words	262	278
Additional payment (cents)	36	84

Fixed payment for 250 words is $31. Find the equation representing the above data.

• A. $y=2x+3100$
• B. $y=3x+2500$
• C. $y=2x+2500$
• D. $y=3x+3100$

Answer 1

The correct option is D $y=3x+3100$

Here it is given that,
Initial value for 250 words $=\$31$
$=3100cents$


You know,
$\text{Rate of change = slope =}\frac{Changeiny}{Changeinx}$

Consider the points (262,36) and (278,84).

By putting the values from graph, you get:
$\text{Slope (m)}=\frac{84-36}{278-262}$
$=\frac{48}{16}$
$=3$

∴ The rate of change is 3 cents/extra word.

You know, equation of a straight line is $y=mx+c$

So, by putting the value, you get the equation of the straight line as:
$y=3x+3100$