An element with a mass of 910 grams decays by 27.4% per minute. To the nearest minute, how long will it be until there are 10 grams of the element remaining?Answer:
Q. An element with a mass of 910 grams decays by 27.4% per minute. To the nearest minute, how long will it be until there are 10 grams of the element remaining?Answer:
Identify amounts and rate: Identify the initial amount, final amount, and the decay rate per minute.Initial amount a = 910 gramsFinal amount y = 10 gramsDecay rate per minute = 27.4%
Convert rate to decimal: Convert the decay rate from a percentage to a decimal for calculation purposes.Decay rate per minute = 27.4%=10027.4=0.274
Use exponential decay formula: Use the exponential decay formula y=a×(1−r)t, where y is the final amount, a is the initial amount, r is the decay rate, and t is the time in minutes.We need to solve for t when y=10 grams, a=910 grams, and r=0.274.10=910×(1−0.274)t
Isolate exponential part: Divide both sides of the equation by 910 to isolate the exponential part of the equation.91010=(1−0.274)t
Simplify left side: Simplify the left side of the equation.91010≈0.010989010.01098901=(1−0.274)t
Take natural logarithm: Take the natural logarithm (ln) of both sides to solve for t.ln(0.01098901)=ln((1−0.274)t)
Bring down exponent: Use the property of logarithms that ln(ab)=b×ln(a) to bring down the exponent t.ln(0.01098901)=t×ln(1−0.274)
Calculate logarithms: Calculate ln(1−0.274) and ln(0.01098901) using a calculator.ln(1−0.274)≈ln(0.726)≈−0.319ln(0.01098901)≈−4.512
Solve for t: Divide both sides of the equation by ln(1−0.274) to solve for t.t=ln(1−0.274)ln(0.01098901)t≈−0.319−4.512
Round to nearest minute: Calculate the value of t using the values from the previous step.t≈−4.512/−0.319t≈14.144
Round to nearest minute: Calculate the value of t using the values from the previous step.t≈−0.319−4.512t≈14.144Since we cannot have a fraction of a minute in this context, we round t to the nearest whole minute.t≈14 minutes
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