Answer:
rounding to two decimal places: 11.11%
Step-by-step explanation:
we can se the approximate formula for YTM
C= 57.5 (1,000 x 11.5%/2)
Face value = 1000
P= 1050 (market value)
n= 24 (12 years x 2 payment per year)
semiannual YTM = 5.4065041%
This is a semiannual rate as we consider semiannula payment.
We need to convert into annual rate:

YTM 11.1053109921343000%
rounding to two decimal places: 11.11%