Question on Arbitragefree Valuation and Spot Rates note, 1030, understand, selling, already

hanvinh

Consider a 6% Treasury note with 1.5 years to maturity. Spot rates (EXPRESSED AS SEMIANnUAL YIELDS TO MATURITY) are: 6 months = 5%, 1 year = 6%, 1.5 years = 7%. If the note is selling for $992, compute the arbitrage profit, and explain how a dealer would perform the arbitrage.
Now… the part I’m confused about is the explanation. It shows the PV formulas… 30/1.025) + 30/(1.03)^s + 1030/(1.035)^3.
What I don’t understand is why are the dividing the given spot rates by two? It already said they are given as semiannual so why are they divided by 2 again?