Which is better investment : 11% stock at 143 (or) 9 3/4% stock at 117 ?

Let investment in each case be Rs. (143 x 117).

Income in 1st case = Rs. $\frac{11}{143}$ x 143 x 117 = Rs. 1287.
Income in 2nd case = Rs. $\frac{39}{4\times 117}$ x 143 x 117= Rs. 1394.25

Clearly, 9 3/4% stock at 117 is better.