Where did the 50 come from?

Suppose in year t you bought a 10% coupon bond (annualized coupon rate) with YTM =5% (semi-annual yield), face value =$1,000, and maturity =15 years. Next half year, the YTM rise from 5\% to 10%. Calculate the return on your half year holding of this bond. - Pt=50(0.0510.05(1+0.05)301)+(1+0.05)301000=1000 - Pt1=50(0.110.1(1+0.1)291)+(1+0.1)291000=531.52 - RETt1=100050+1000531.521000=41.85%