Shell, Mobil and Total are the three competing companies in the petroleum market of Ethiopia Each company retains 70% of its customer every month in addition every month 10% of the customers of Shell switch to Mobil while 20% switch to Shell Moreover, 15% of the customers of Total switch to Mobil every month. What will be the respective market shares of the three companies for the months March and May if their market share in February is 30% Shell, 20% Total and 50% Mobil.​