# Question #dfe82

##### 1 Answer
Nov 30, 2016

The call lasted between five and six minutes.

#### Explanation:

If the call lasts more than $k - 1$ but less then $k$ minutes, the cost is:

$C = 0.24 + \left(k - 1\right) \cdot 0.18$

As $C = 1.14$:

$1.14 = 0.24 + \left(k - 1\right) \cdot 0.18$

$1.14 - 0.24 = \left(k - 1\right) \cdot 0.18$

$0.9 = \left(k - 1\right) \cdot 0.18$

$\frac{0.9}{0.18} = k - 1$

$5 = k - 1$

$k = 6$