Financial Risk Management Part 1

Book 4 - Reading 55: Bond Yields and Return Calculations

My question is regarding the explanation above. Why is the I/Y 4.625 in the explanation? It does not show in the problem and I want to know how to get that so I can understand how to solve the problem. Thank you :)

A $1,000 par bond carries a coupon rate of 10%, pays coupons semiannually, and has 13 years remaining to maturity. Market rates are currently 9.25%. The price of the bond is closest to: A) $586.60. B) $1,036.03. C) $1,055.41. D) $1,056.05. Explanation N=26;PMT=50;I/Y=4.625;FV=1,000;CPTPV=$1,056.05(LO55.c)