In the last quarter of $2017,$ a group of $64$ mutual funds had a mean return of $4\mathrm{.}2\%$ with a standard deviation of $4\mathrm{.}9\%.$ If a Normal model can be used to model them, what percent of the funds would you expect to be in each region? Use the $68-95-99\mathrm{.}7$ rule to approximate the percentages rather than using technology to find the values more precisely. Be sure to draw a picture first.

a$)$ Returns of $9\mathrm{.}1\%$ or more

b$)$ Returns of $4\mathrm{.}2\%$ or less

c$)$ Returns between $-10\mathrm{.}5\%$ and $18\mathrm{.}9\%$

d$)$ Returns of more than $14\mathrm{.}0\%$