The following data table represents the total cost of a monthly cell phone bill as a function of the number of minutes that the phone is used each month.
minutes 500 750 1,000 1,250 1,500
total monthly cost (in dollars) $62 $77 $92 $107 $122
choose the correct linear model that represents the total monthly cost as a function of time.
y = 0.06x + 500
y = 16x + 32
y = 62x + 16
y = 0.06x + 32

answer:

d. 0.06x + 32

step-by-step explanation:

it needs high-low method of cost to determine variable and fixed cost, and then find the cost function.

given,

highest activity = 1500 minutes

lowest activity = 500 minutes

higest cost = $122

lowest cost = $62

we know, variable cost under high-low method = (highest cost - lowest cost) / (highest activitiy - lowest activity)

therefore, variable cost = $(122 - 62)/(1500 - 500) minutes

variable cost = $60/1000 = $0.06

fixed cost = total cost in highest activity - variable cost per minute * highest activity

fixed cost = $122 - ($0.06*1500)

fixed cost = $122 - $90 = $32

therefore, liner cost function = variable cost per minute * fixed cost

y = 0.06x + $32

therefore, d is the answer.

correct choice is b

step-by-step explanation:

when you calculate the average rate of change of a function, you are finding the slope of the secant line between the two points. for the function the average rate of change from point to point can be calculated as

to find the average rate of change from day 2 to day 10, note that at day 2, 8 houses were sold, so a(2,8) and at day 10, 2 houses were sold, so b(10,2). thus,

let y equal to

the total fare and x is the mile of taxi ride. so the equation is

y = 0.55x + 1.75

since susie has

$10 to spend for a taxi cab, so he can have

10 = 0.55x +

1.75

x = 15 miles of

taxi ride

so the system of

inequality is

10 < 0.55x +

1.75

x > 2