In a lab experiment, the decay of a radioactive isotope is being observed. At the beginning of the first day of the experiment the mass of the substance was 1400 grams and mass was decreasing by 12% per day. Determine the mass of the radioactive sample at the beginning of the 18th day of the experiment. Round to the nearest tenth (if necessary).Answer: □ grams
Q. In a lab experiment, the decay of a radioactive isotope is being observed. At the beginning of the first day of the experiment the mass of the substance was 1400 grams and mass was decreasing by 12% per day. Determine the mass of the radioactive sample at the beginning of the 18th day of the experiment. Round to the nearest tenth (if necessary).Answer: □ grams
Identify initial mass and decrease: Identify the initial mass and the daily percentage decrease.The initial mass of the radioactive substance is 1400 grams, and it decreases by 12% each day.
Determine decay factor: Determine the decay factor.Since the mass decreases by 12% each day, the decay factor is 100%−12%=88% per day. To use this in calculations, convert the percentage to a decimal by dividing by 100. Thus, the decay factor is 0.88.
Calculate mass at 18th day: Calculate the mass at the beginning of the 18th day.The formula for exponential decay is given by P(t)=P0×(decay factor)t, where P(t) is the final mass, P0 is the initial mass, and t is the time in days.For this problem, P0=1400 grams, the decay factor is 0.88, and t=17 (since we want the mass at the beginning of the 18th day, we use t=17 days).P(17)=1400×(0.88)17
Perform calculation: Perform the calculation.P(17)=1400×(0.88)17Using a calculator, we find:P(17)≈1400×0.114P(17)≈159.6
Round result: Round the result to the nearest tenth. The mass of the radioactive sample at the beginning of the 18th day is approximately 159.6 grams when rounded to the nearest tenth.
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