An element with mass 650 grams decays by 29.5% per minute. How much of the element is remaining after 20 minutes, to the nearest 10th of a gram?Answer:
Q. An element with mass 650 grams decays by 29.5% per minute. How much of the element is remaining after 20 minutes, to the nearest 10th of a gram?Answer:
Identify: Identify the initial amount, decay rate per minute, and total time.Initial amount a = 650 gramsDecay rate per minute r = 29.5%Total time t = 20 minutesWe need to calculate the remaining amount of the element after 20 minutes.
Convert Rate: Convert the decay rate from a percentage to a decimal.To convert a percentage to a decimal, divide by 100.r=10029.5%=0.295
Calculate Percentage: Calculate the remaining percentage after each minute.Since the element decays by 29.5% each minute, it retains 100%−29.5%=70.5% of its mass each minute.Remaining percentage per minute = 100%−29.5%=70.5%Convert this to a decimal: 70.5%/100=0.705
Use Exponential Decay: Use the exponential decay formula to calculate the remaining amount after 20 minutes.The formula for exponential decay is:remaining amount = initial amount ×(1−decay rate)timeSubstitute the values into the formula:remaining amount = 650×(0.705)20
Calculate Remaining Amount: Calculate the remaining amount using the values from Step 4.remaining amount=650×(0.705)20Use a calculator to find (0.705)20.(0.705)20≈0.016258Now, multiply this by the initial amount:remaining amount≈650×0.016258remaining amount≈10.5677
Round to Nearest: Round the remaining amount to the nearest 10th of a gram.The remaining amount rounded to the nearest 10th of a gram is approximately 10.6 grams.
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