Suppose the term structure over 4 years is given as follows: s1 = 2.9%, s2 = 3.2%, s3 = 3.6% and s4 = 4.2%.

Question: Suppose that someone offers to commit to borrowing money from you between years 3 and 4 at a rate of 6.3%. Assume you can access (borrow or lend) all implied forward rates from an ideal bank. Provide details (specific trades) of how you can construct an arbitrage.