The line chart illustrates the average monthly contract cost for four different mobile phones (Demo, Lex, Sim TX, and Alpha) in a European country from January to September 2002, measured in euros.
Overall, it is evident that the costs of three of the mobile phones experienced significant fluctuations over the period, while Sim TX witnessed a steady decline.
To begin with, the cost of the Alpha cell phone was the lowest in January, starting at 5 euros. It experienced fluctuations throughout the period, rising to 7 euros in April, dipping in June, and then showing a slight increase from June to September, reaching 25 euros.
In contrast, the Demo cell phone had the highest cost in January, starting at 15 euros. Its cost saw a dramatic rise in July, peaking at approximately 23 euros, before declining slightly to around 20 euros by September. The trajectory of the Lex and Sim TX cell phones followed a similar pattern, with both starting at approximately 10 euros in January..