a man earns rs. 24,000 pm. he spends 1/3rd of his income on personal expenditures. half of the remaining income is invested in a scheme at 15% interest pa. after investing, half of what is left is invested in a scheme which gives 10% interest pa. the remaining lies in a bank, where it earns an interest of 4% pa. the effective rate of interest earned by the man on his investments at the end of the year is?