An element with a mass of 220 grams decays by 26.6% per minute. To the nearest tenth of a minute, how long will it be until there are 10 grams of the element remaining?Answer:
Q. An element with a mass of 220 grams decays by 26.6% per minute. To the nearest tenth of a minute, how long will it be until there are 10 grams of the element remaining?Answer:
Understand the decay process: Understand the decay process.The decay process can be described by the exponential decay formula: N(t)=N0×(1−r)t, where N(t) is the remaining amount after time t, N0 is the initial amount, r is the decay rate per time period, and t is the time period.
Convert to decimal: Convert the percentage decay rate to a decimal.26.6% as a decimal is 0.266.
Set up equation: Set up the equation with the given values.We have N0=220 grams, N(t)=10 grams, and r=0.266. Plugging these into the decay formula gives us 10=220×(1−0.266)t.
Simplify the equation: Simplify the equation.Divide both sides by 220 to isolate the exponential expression: 22010=(1−0.266)t.
Calculate left side: Calculate the left side of the equation. 22010 simplifies to 221.
Take natural logarithm: Take the natural logarithm of both sides to solve for t.ln(221)=ln((1−0.266)t).
Use logarithm property: Use the property of logarithms to bring down the exponent.ln(221)=t×ln(1−0.266).
Calculate ln values: Calculate ln(1−0.266) and ln(221).ln(1−0.266)≈ln(0.734) and ln(221)≈ln(0.04545).
Divide to solve: Divide to solve for t.t=ln(0.734)ln(0.04545).
Calculate t value: Calculate the value of t.t≈ln(0.04545)/ln(0.734)≈−3.09104/−0.30952≈9.987, which rounds to 10.0 to the nearest tenth of a minute.
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