Question

The fixed price of renting a stage is ₹80 for the first 6 hours, and ₹4 is charged as an additional maintainance amount per hour. Find the total amount charged for renting the stage for 10 hours.

• A. ₹80
• B. ₹100
• C. ₹120
• D. ₹140

Answer 1

The correct option is C ₹120

Consider the points (0,80) and (20,160) on the graph


You know,
$\text{slope = unit rate =}\frac{y_2-y_1}{x_2-x_1}$

So, by putting the values you get,
$\text{slope =}\frac{₹160-₹80}{20-0}$
$=\frac{₹80}{20}$
$=₹4$

$\text{Equation of a straight line is:}y=mx+c$

Also, amount charged when the extra hours were zero will be equal to the y-intercept (c).

From the graph, you can see that
$\text{value of y-intercept (c) =}₹80.$

So, the amount required for 10 extra hours will be
$y=4x+c$

$\Rightarrow y=₹4\times 10+₹80$

$\Rightarrow y=₹120$

∴ Amount charged for 10 extra hours will be ₹120.