The consumer must use at least a time of 333 minutes in order for the second plan to be preferable.
Herein we have to determine for what number of minutes the second cell phone plan is preferable, this can be found by using an inequality of the form x(t) > y(t), where t is the time, in minutes. The expressions for the two plans and the inequality itself are, respectively:
First plan
c = 0.24 · t (1)
Second plan
c = 39.95 + 0.12 · t (2)
Inequality
0.24 · t > 39.95 + 0.12 · t
Please notice that the second plan is preferable when cost is lower than in the first plan.
0.12 · t > 39.95
t > 332.916
The consumer must use at least a time of 333 minutes in order for the second plan to be preferable.
To learn more on inequalities: https://brainly.com/question/20383699
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