John Cena borrows $500,000$ from Ashley Tisdale. Cena will repay Tisdale with $72$ end of month payments. The nominal interest rate is $7\mathrm{.}2\%$ convertible monthly. Cena's first $24$ payments are $x,$ the second $24$ payments are $2x$ and the third $24$ payments are $3x.$ Just after the $48$th payment has been made, Tisdale sells the remaining payments to Miley Cyrus. The price Cyrus pays is based on a nominal interest rate of $8\mathrm{.}4\%$ convertible monthly. Calculate the nominal yield rate for Tisdale convertible monthly.