Respuesta :
Answer:
In other words, the executive plan is cheaper.
562.5 minutes, any plan is indifferent to it.
Step-by-step explanation:
We have to Kim will use the phone 21 hours a month, that in minutes would be equal to:
21 h * (60 m / 1 h) = 1260 minutes
Now, let's pose each case.
Regular plan, which give away a total of 1000 minutes, therefore Kim must pay extra charge 1260 - 1000 = 260. Now we have to:
$ X = Fixed charge + Extra charges
We know that the fixed charge is $ 55 and that for each extra minute it is $ 0.33, replacing
$ X = 55 + 260 * 0.33 = $ 140.8
Executive plan, which give away a total of 1200 minutes, therefore Kim must pay extra charge 1260 - 1200 = 60. Now we have to:
$ Y = Fixed charge + Extra charges
We know that the fixed charge is $ 100 and that for each extra minute it is $ 0.25, replacing
$ Y = 100 + 60 * 0.25 = $ 115
In other words, the executive plan is cheaper.
It is indifferent when X and Y are equal, we calculate the number of minutes (m) when these values are equal. So:
55 + m * 0.33 = 100 + m * 0.25
0.33 * m - 0.25 * m = 100 - 55
0.08 * m = 45
m = 45 / 0.08
m = 562.5
That is, when in both cases, the number of extra minutes that must be paid equals 562.5, any plan is indifferent to it.
Answer:
She should select the second plan, since she'd pay 125 $ for that instead of 140.8 $ for the first one.
To be indifferent between the plans she'd have to use 2312.5 minutes per month.
Step-by-step explanation:
First plan:
value to pay = 55 + variable amount
if minutes used are greater than 1000:
variable amount = (minutes used - 1000)*0.33
Second plan:
value to pay = 100 + variable amount
if minutes used are greater than 1200:
variable amount = (minutes used - 1200)*0.25
If she wants to use her phone for 21 h per month that is the same as 21*60 = 1260 minutes per month so:
Plan 1: value to pay = 55 + (1260-1000)*0.33 = 55 + 85.8 = 140.8 $
Plan2: value to pay = 100 + (1260-1200)*0.25 = 60 + 65 = 125 $
In this case she should select the first plan.
To compute the value both plans are equal we need to equate both expressions, so we have:
55 + (minutes used - 1000)*0.33 = 100 + (minutes used - 1200)*0.25
55 + 0.33*(minutes used) - 330 = 100 + 0.25*(minutes used) -300
0.33*(minutes used) - 0.25*(minutes used) = 55 + 330 + 100 - 300
0.08*(minutes used) = 185
minutes used = 2312.5
She would have to use 2312.5 minutes in order to be indifferent between the plans.
