Calculating the risk premium on bonds

$(1+i)=(1-p)(1+i+x)+p(0)$

$p$ is the probability that the bond does not pay at all $($the bond issuer is bankrupt$)$ and has a zero return.

$i$ is the nominal policy interest rate.

$x$ is the risk premium.

a$.$ If the probability of bankruptcy is zero, what is the rate of interest on the risky bond?

b$.$ Calculate the probability of bankruptcy when the nominal interest rate for a risky borrower is $8\%$ and the nominal policy rate of interest is $3\%.$

c$.$ Calculate the nominal interest rate for a borrower when the probability of bankruptcy is $1\%$ and the nominal policy rate of interest is $4\%.$

d$.$ Calculate the nominal interest rate for a borrower when the probability of bankruptcy is $5\%$ and the nominal policy rate of interest is $4\%.$

e$.$ The formula assumes that payment upon default is zero. In fact, it is often positive. How would you change the formula in this case?