Question

Algebra 1 class

Write an expression that can be used to find the cost of an n-minute long distance call, where n is at least 5 minutes.
Look At picture of table

Answer 1

y = 0.07n + 0.2

Explanation:

y = mx + b

m: slope → amount cost is increasing

b: y-intercept → the cost at 0 minutes

cost is increasing by (m): 0.07 cost increase by minute

Time at 5 minutes + the amount cost increase = Time at 5 minutes

0.55 + m = 0.62

-0.55 -0.55 m = 0.07

Time at 6 minutes + the amount cost increase = Time at 5 minutes

0.62 + m = 0.69

-0.62 -0.62 m = 0.07

....and so on

the cost at 0 minutes (b): 0.2 is the cost at 0 minute (start)

cost at n minutes

= cost is increasing by (m) x n of minutes + cost at 0 minutes (b)

cost at 5 minutes

= cost is increasing by (m) x 5 minutes + cost at 0 minutes (b)

0.55 = 0.07 x (5) + b

0.55 = 0.35 + b

- 035 - 035

b = 0.2