An investor bought a $63$-day Treasury bill with a face value of $\$105000$ to yield $3.55$%. The investor sold the T-bill $23$ days later to another investor who yields $2.8$%. What rate of return did the original investor realize?
So right off the start I find the $P$ by doing $$P = 105000/(1+0.0355(63/365)) = 104360.5415$$
Then $$S = 104360.5415(1+0.028(23/365)) = 104544.6734.$$
Rate of return would be = $(104544.6734-104360.5415)/(104360.5415)$
Can someone let me know what I'm doing wrong, thanks