Question $8\mathrm{.}19$

A perpetuity$-$immediate pays $300$ at the end of the first year, $325$ at the end of the second

year, $350$ at the end of the third year, and so on$.$ The present value of the perpetuity$-$

immediate is $21,315.$

The annual effective rate of interest is $i.$

Calculate $i.$

A $2\mathrm{.}1\%$

B $2\mathrm{.}8\%$

C $4\mathrm{.}1\%$

D $4\mathrm{.}2\%$

E $8\mathrm{.}4\%$

The answer should be D$.4\mathrm{.}2\%$ but I don't know how to get to that answer.