Sarah invested $8,000 in a savings account. After 10 years, her investment grew to $12,000. What is the annual interest rate, compounded continuously, that Sarah's account earned? Round your answer to the nearest two decimal places in percentage form. Use the formula A=Pert, where A is the balance (final amount), P is the principal (starting amount), e is the base of natural logarithms (≈2.71828), r is the interest rate expressed as a decimal, and t is the time in years.
Q. Sarah invested $8,000 in a savings account. After 10 years, her investment grew to $12,000. What is the annual interest rate, compounded continuously, that Sarah's account earned? Round your answer to the nearest two decimal places in percentage form. Use the formula A=Pert, where A is the balance (final amount), P is the principal (starting amount), e is the base of natural logarithms (≈2.71828), r is the interest rate expressed as a decimal, and t is the time in years.
Identify Values: Identify the given values: A = $12,000 P = $8,000 t = 10 \text{ years} Use the formula A=Pert.
Rearrange Formula: Rearrange the formula to solve for r: A=Pert12,000=8,000imese10r Divide both sides by 8,000: rac{12{,}000}{8{,}000} = e^{10r} 1.5=e10r
Take Natural Logarithm: Take the natural logarithm (\ln) of both sides to solve for r: ln(1.5)=ln(e10r)ln(1.5)=10r
Isolate r: Divide both sides by 10 to isolate r:r=ln(1.5)/10
Calculate r: Calculate the value of r:r≈ln(1.5)/10r≈0.4055/10r≈0.04055
Convert to Percentage: Convert r to a percentage: r≈0.04055×100r≈4.06%