(a)[3]
A book's price rises from $\$2.50$ to $\$2.65$. Calculate the percentage increase.
(b)[3]
Scott puts $\$500$ into an investment for 7 years at a simple interest rate of $1.5\%$ per year. Calculate the value of his investment after the 7 years.
(c)[2]
A city’s population is growing exponentially by $1.6\%$ each year. Find the overall percentage increase after 20 years.
(d)[3]
Calculate the value of $r$.