Question #dfe82

1 Answer
Nov 30, 2016

The call lasted between five and six minutes.

Explanation:

If the call lasts more than k1 but less then k minutes, the cost is:

C=0.24+(k1)0.18

As C=1.14:

1.14=0.24+(k1)0.18

1.140.24=(k1)0.18

0.9=(k1)0.18

0.90.18=k1

5=k1

k=6