Problema Solution
An internet provider charges 30 dollars per month for 1000 minutes of DSL service plus each 0.08 dollars for additional minute. In a one-year period the customer's bill ranged from 34.40 dollars to 47.60 dollars. What were the most and least minutes used?
Answer provided by our tutors
let x=the number of minutes used
34.40 <= 30 + (x - 1000)0.08 <= 47.60
34.40 - 30 <= (x - 1000)0.08 <= 47.60 - 30
4.40 <= (x - 1000)0.08 <= 17.60
4.40/0.08 <= x - 1000 <= 17.60/0.08
4.40/0.08 + 1000 <= x <= 17.60/0.08 + 1000
1055 <= x <= 1220
the most minutes used is 1220 minutes.
the least minutes used is 1055 minutes.