The lifetime, in years, of a certain type of fuel cell is a random variable with probability density function 81 f (x) = (x + 3)4 x > 0 0 x ≤ 0 a. what is the probability that a fuel cell lasts more than 3 years? b.

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 25, a standard deviation of 2.5, and margin of error of 5%

Layla answer 21 of the 25 questions on his history test correctly. what decimal represents the fraction of problem he answer incorrectly.

The perimeter of ? cde is 55 cm. a rhombus dmfn is inscribed in this triangle so that vertices m, f, and n lie on the sides cd , ce , and de respectively. find cd and de if cf=8 cm and ef=12 cm. the answer is not cd=20 and de=15. i have tried that one, it does not work.