After 2 hours, $82.75. After 6 hours, $360.75. How much after 8 hours?

Question

Concession stand vendor ^

Answer 1

You could work out an equation, using the two points in time as if they are points on an x-y plane.  Then you could plug in 8 hours for x and see what you get for y.

 

There's an easier way, though.  Notice that between the 2 hour point and the 6 hour point, 4 hours have passed, and the amounts have increased by $360.75 - $82.75 = 278.  That's a rate of 278 / 4 = $69.50 per hour.

 

To get to the 8-hour point, that's two more hours past the 6-hour point, where the amount was $360.75.  So two additional hours, at $69.50 per hour, is $139.  So add $139 to the 6-hour amount, $360.75, to get the 8-hour amount.  That gives you $499.75.