Sam initially invested $4,500 into a savings account that offers an interest rate of 3% each year. He wants to determine the number of years, t, for which the account will have less than or equal to $7,020.

Respuesta :

gmany

Every year, Sam will have 103% of the amount from the previous year.

[tex]p\%=\dfrac{p}{100}\\\\103\%=\dfrac{103}{100}=1.03[/tex]

After the first year:

[tex]1.03\cdot\$4,500[/tex]

After the second year:

[tex]1.03\cdot1.03\cdot\$4,500=\$4,500(1.03)^2[/tex]

After the t-th year:

[tex]\$4,500(1.03)^t[/tex]

Therefore we have the inequality:

[tex]\$4,500(1.03)^t\leq\$7,020\ \ \ \ |\text{divide both sides by \$4,500}\\\\(1.03)^t\leq1.56\\\\(1.03)^{15}\approx15.56\\\\\text{therefore}\ t\leq15[/tex]

Answer: t ≤ 15.