John has a loan of $50,000$ which is being repaid with non$-$level payments over $15$ years.

The first payment is $4000$ at the end of one year. The second payment is $8000$ at the end

of two years. The third payment of $5000$ at the end of three years. The fourth payment of

$9000$ at the end of four years. The annual effective interest rate on the loan is $4\mathrm{.}75\%.$

Determine the outstanding loan balance right after the payment of $5000$ at the end of

three years.