We solve \( e^{-0.05t} = 0.25 \).

["# Solving the Equation ( e^{-0.05t} = 0.25 ): A Step-by-Step Guide", "Understanding how to solve exponential equations is a fundamental skill in mathematics, physics, engineering, and data science. One common type of equation you may encounter is exponential decay models, represented by equations like ( e^{-kt} = C ), where ( t ) is time ($ t $), $ e $ is Euler’s number, $ k $ is the decay constant, and $ C $ is a constant value.", "In this article, we’ll break down how to solve the equation:", "[\ne^{-0.05t} = 0.25\n]", "This equation appears frequently in scientific applications such as radioactive decay, pharmacokinetics, or any process modeled with exponential decay. Solving it helps determine the time $ t $ it takes for a quantity to reduce to 25% of its initial value.", "---", "## Step 1: Understand the Equation", "Given:", "[\ne^{-0.05t} = 0.25\n]", "Here, the function ( e^{-0.05t} ) describes a quantity decaying exponentially over time at a rate governed by the constant 0.05. We seek $ t $ such that at time $ t $, the value of this expression equals 0.25.", "---", "## Step 2: Apply Natural Logarithm to Both Sides", "To remove the exponential, take the natural logarithm ($ \ln $) of both sides:", "[\n\ln\left(e^{-0.05t}\right) = \ln(0.25)\n]", "Using the logarithmic identity ( \ln(e^x) = x ), the left side simplifies:", "[\n-0.05t = \ln(0.25)\n]", "---", "## Step 3: Solve for $ t $", "Now isolate $ t $ by dividing both sides by $-0.05$:", "[\nt = \frac{\ln(0.25)}{-0.05}\n]", "Note: ( \ln(0.25) = \ln\left(\frac{1}{4}\right) = -\ln(4) )", "So,", "[\nt = \frac{-\ln(4)}{-0.05} = \frac{\ln(4)}{0.05}\n]", "---", "## Step 4: Compute the Value", "We know that ( \ln(4) = \ln(2^2) = 2\ln(2) \approx 2 \ imes 0.6931 = 1.3862 )", "Thus:", "[\nt \approx \frac{1.3862}{0.05} = 27.724\n]", "---", "## Step 5: Interpret the Result", "The solution ( t \approx 27.72 ) means it takes approximately 27.72 time units for the quantity modeled by ( e^{-0.05t} ) to reduce to 25% of its initial value.", "---", "## Why This Equation Matters", "Exponential decay equations like ( e^{-kt} = C ) are essential in:", "- Physics: Radioactive half-life calculations\n- Medicine: Drug concentration over time\n- Engineering: Battery discharge, cooling processes, or signal attenuation", "Mastering how to solve such equations empowers you to predict system behavior and make informed decisions based on decay dynamics.", "---", "## Summary", "To solve ( e^{-0.05t} = 0.25 ):", "1. Take the natural logarithm of both sides\n2. Use logarithmic properties to isolate $ t $\n3. Substitute known values and compute", "Final result:\n[\n\boxed{t = \frac{\ln(4)}{0.05} \approx 27.72}\n]", "---", "## Next Steps", "- Learn how to solve logarithmic equations in more complex forms.\n- Apply exponential models to real-world scenarios using ( y = ae^{kt} ).\n- Explore solved examples involving half-lives, doubling time, and decay constants.", "By practicing these techniques, you’ll build strong mathematical tools for scientific and analytical challenges.", "---", "Keywords: exponential decay, solve ( e^{-0.05t} = 0.25 ), natural logarithm, algebra, real-world equations, mathematical modeling, decay constants, scientific calculations."]