Asap! billy is monitoring the exponential decay of a radioactive compound. he has a sample of the compound in a test tube in his lab. according to his calculations, the sample is decaying at a rate of 35% per hour. there are at least 72 grams of the sample remaining. once the sample reaches a mass of 15 grams, billy will continually add more of the compound to keep the sample size at a minimum of 15 grams.

if r represents the actual amount of the sample remaining, in grams, and t represents the time in hours, then which of the following systems of inequalities can be used to determine the possible mass of the radioactive sample over time?

The weibull distribution is widely used in statistical problems relating to aging of solid insulating materials subjected to aging and stress. use this distribution as a model for time (in hours) to failure of solid insulating specimens subjected to ac voltage. the values of the parameters depend on the voltage and temperature; suppose α = 2.5 and β = 190. (a) what is the probability that a specimen's lifetime is at most 250? less than 250? more than 300? (round your answers to four decimal places.) at most 250 less than 250 more than 300 (b) what is the probability that a specimen's lifetime is between 100 and 250? (round your answer to four decimal places.) (c) what value is such that exactly 50% of all specimens have lifetimes exceeding that value? (round your answer to three decimal places.) hr