which is better investment: 7.5% stock at 105 or 6.5% stock at 94

Which is better investment 11% stock at 143 or 9(3)/(4)% stock at 117?( a )11% stock at 143 (b) 9(3)/(4)% stock at 117 (c) both are equally good (d) Cannot be compared,as the total amount of investment is not given

Which is better investment,12% stock at par with an income tax at the rate of 5 paise per rupee or 14(2)/(7)% stock at 120 free from income tax? (a) 12% stock (b) 14(2)/(7)% stock (c) Both are equally good (d) Cannot be compared

9800 are invested partly in 9% stock at 75 and 10% stock at 80 to have equal amount of incomes.The investment in 9% stock is (a) Rs 4800 (b) Rs 5000 (c) Rs 5400 (d) Rs 5600