Element X is a radioactive isotope such that every 69 years, its mass decreases by half. Given that the initial mass of a sample of Element X is 20 grams, how much of
the element would remain after 30 years, to the nearest whole number?

Acircle has a circumference of 7.850 units. what is its radius?

Find the distance between (7,-6) and (-3,-9)

A. find the power of the test, when the null hypothesis assumes a population mean of mu = 450, with a population standard deviation of 156, the sample size is 5 and the true mean is 638.47 with confidence intervals of 95 b. find the power of the test, when the null hypothesis assumes a population mean of mu = 644, with a population standard deviation of 174, the sample size is 3 and the true mean is 744.04 with confidence intervals of 95% c. find the power of the test, when the null hypothesis assumes a population mean of mu = 510, with a population standard deviation of 126, the sample size is 10 and the true mean is 529.44 with confidence intervals of 95