Question

A monthly phone bill, b(m), consists of a $22 service fee plus $0.12 per minute, m, of long distance calls, given by the function (m) = 22 + 0.12m. Draw a graph for up to and including 120 minutes of long distance calls made in a month. Estimate the bill if 93 minutes of long distance calls are made.

Answer 1

∵ The graph represents b(m) = 22 + 0.12 m , where

→ m is the number of the minutes

→ b(m) is the cost of the calls

∵ x = 93 minutes

→ Look at the graph and try to find the value of b(93)

∵ 4 intervals on the b(m) axis and m axis represent 200

∴ Each interval = 200/4 = 50 dollars and 50 minutes

• Then 93 will be nearest to the second intervals go up to find the value of b(m)

∴ b(93) = 35 means between 30 and 40

The bill will be about $35