The line graph illustrates the median monthly cost of 4 kind of mobile phones across the period from January to September in a European country in 2002. Overall, the most significant jump over the period in monthly payment was in company Sim TX. It is also clear that Demos’ payment cost was the highest and experienced dramatical rises before slightly decreasing. However, Lex and Alpha almost mirrored the opposite pattern.
Starting at 15 euros in January, monthly cost for mobile phones in Demo grew slightly and to May its price was 20 euros, following consistent increases the cost reached 25 euros per month before dropping to approximately 23 euros by September. However, the Sim TX showed fluctuation between January and June, after which the price fell to 5 euros, followed by small decreases the cost resurged and reached 25 euros per month in September.
The company Lex and Alpha almost recorded the opposite trends. In the period from January to June in Alpha the monthly price saw brief increase to about 14 euros, which then followed significant drop to 8 euros by September. The Lex over the same period experienced slight fluctuation and by June to September, its monthly cost increased stably and reached approximately 18 euros.