Problem # $8$: An initial deposit of $$10000$ is made into an account now, and a second deposit of

$$16000$ is made into the same account after $15$ years. During the first $10$ years, the

account earns interest quoted at a nominal quarterly discount rate of $d\%.$ After $10$

years have passed, any money in the account earns a nominal semi$-$annual interest

rate of $4\mathrm{.}2\%.$ At the end of $30$ years, the total value of the account will be $$70207.$

What is the value of $d($to the nearest $0\mathrm{.}1\%)?$