$($Compound value solving for r$)$ At what annual rate would the following have to be invested?

a$.$ $$480$ to grow to $$1$ comma $238\mathrm{.}60$ in $11$ years

b$.$ $$310$ to grow to $$566\mathrm{.}69$ in $7$ years

c$.$ $$50$ to grow to $$363\mathrm{.}17$ in $19$ years

d$.$ $$216$ to grow to $$252\mathrm{.}69$ in $4$ years