1 Riphean plc and Silurian plc are two businesses operating in different industries. They are both financed by a mixture of ordinary share and loan capital and both are seeking to derive the cost of capital for investment decision-making purposes. The following information is available concerning the two businesses for the year to 30 November Year 8 : The annual growth rate in dividends is 5 per cent for Riphean plc and 8 per cent for Silurian plc. Assume a 30 per cent tax rate. Required: (a) Calculate the weighted average cost of capital of Riphean plc and Silurian plc using the information provided. (b) Discuss two possible reasons why the cost of ordinary share capital differs between the two businesses. (c) Discuss two limitations of using the weighted average cost of capital when making investment decisions