Question

Rai is considering two mobile phone plans that charge. For each call made the charges are shown below
Mobile plan a monthly subscription $10 cost per minute 21.4 cents per minute
Mobile plan b monthly subscription $14 cost per minute 18.5 cents minutes

On average rai uses n minutes of calling time each month
A) write an expression for the total charges for rais usage based in each mobile plan
B) if n= 100 find the total cost for each mobile plan which mobile plan should rai choose ?? Justify your choice

Answer 1

A)
For plan a
subscription cost = $10
call rate = 21.4 cents/minute = $ 0.214 
If Rai uses n minutes in a month
Total charges per month = 10 + n×0.214 = $ (10+0.214n)

For plan b
subscription cost = $14
call rate = 18.5 cents/minute = $ 0.185 
If Rai uses n minutes in a month
Total charges per month = 14 + n×0.185 = $ (14+0.185n)

B)
if n=100
charge in plan a = $ (10+0.214×100) = $ 31.4
charge in plan b = $ (14+0.185×100) = $ 32.5
So he should choose plan a.