Question

A cell phone company charges a $10 flat fee plus $0.05 per minute for minutes up to 600. For minutes over 600, the company

charges $0.15 per minute, in addition to the flat fee and the charges for the first 600 minutes.
Which function models the company's cell phone charges?!

Answer 1

In both the cases, the given total amount is given as:

T = 10 + 0.05 m (when minutes talked m < 600)

T = 40 + 0.15 k (when minutes talked k > 600)

Explanation:

Here, the flat fee by the phone company = $10

The charge for each minute for first 600 minutes = $0.05

The per minute cost after 600 minutes = $0.15

Let us assume the number of minutes talked = m

Case 1: when the minutes talked is less than 600 minutes.

Total Charges = Flat Fee + 0.05 x ( the minutes talked)

or, T = $10 + m ($0.05)

or T = 10 + 0.05 m (when m < 600)

Case 2: when the minutes talked is more than 600 minutes.

Let us assume the minutes talked over 600 = k minutes

Total Charges = Flat Fee + Charges for 600 minutes + 0.15 x ( the minutes talked over 600)

or, T = $10 + 600 ($0.05) + k($0.15)

or T = 10 + $30 + 0.15 k (when k > 600)

⇒ T = 40 + 0.15 k (when k > 600)

Hence, in both the cases, the given total amount is given as:

T = 10 + 0.05 m (when m < 600)

T = T = 40 + 0.15 k (when k > 600)