Question

After how many total minutes will it be less expensive to use AT&T instead of 10-10-220 for a long distance phone call? Assume the call is at least 20 minutes.

A) 25 minutes
B) 30 minutes
C) 35 minutes
D) 40 minutes

Answer 1

After 40 minutes, it will be less expensive to use AT&T instead of 10-10-220 for a long-distance phone call.

Step-by-step explanation:

To determine the number of total minutes after which it would be less expensive to use AT&T instead of 10-10-220 for a long-distance phone call, we need to compare the costs of the two services. Let's assume that AT&T charges $0.05 per minute and 10-10-220 charges $10 for 200 minutes.

The cost of using AT&T for x minutes can be calculated as 0.05x, and the cost of using 10-10-220 can be calculated as 10(1 - x/200), as we are assuming the call will be at least 20 minutes.

We can set up an inequality to find the point at which AT&T becomes less expensive: 0.05x < 10(1 - x/200). Solving this inequality will give us the total minutes after which AT&T is less expensive than 10-10-220.

Simplifying the inequality leads to x > 40.

Therefore, after 40 minutes, it will be less expensive to use AT&T instead of 10-10-220 for a long-distance phone call.