Face value is given as ₹ 100 (N.V) ; Sold at 10 % premium
So Market value (M.V) =100+10100×100=110
Amount Invested = ₹ 8800
No. of share he bought =Amount InvestedM.V of 1 share=₹ 8800₹ 110=80
Now Total amount he got at end of year= ₹ 1200
So Total amount = No. of share × Dividend % × M.V
⇒1200=80×Dividend %×100
⇒1200=80×r100×100
r=15%