Raj is deciding between two cell phone plans, a and b, which are both linear functions. the monthly charge for plan a according to the number of minutes used is shown in the table. monthly charge for plan a minutes used, x monthly charge ($), y 0 14.45 3 14.84 6 15.23 9 15.62 12 16.01 plan b has the same monthly base charge as plan a, but it charges a different amount per minute used. if the total monthly charge for plan b is $22.10 when 45 minutes are used, what is the slope of the linear function that represents the cost of plan b? 0.13 0.17 0.39 0.45

Plan A

Monthly Charge for Plan A Minutes used, x    0         3         6             9           12    

Monthly charge ($), y                                    14.45       14.84  15.23     15.62  16.01    

Slope =m =

Linear equation for plan A is

y-14.45=0.13 x [Slope  form of line is , y = m x + c]

y = 0.13 x + 14.45

Given: Plan B has the same monthly base charge as plan A, but it charges a different amount per minute used. If the total monthly charge for plan B is $22.10 when 45 minutes are used

Linear equation for plan B is

y = k x + 14.45

22.10 = k (45) + 14.45

22.10 - 14.45= 45 k

7.65=45 k

k=

Slope of the linear function that represents the cost of plan B=0.17 →→ Option (B).

one set of data has more variation than the other. hope this !