After the release of radioactive material into the atmosphere from a nuclear power plant in a country in 1990 the hay that country was contaminated by a radioactive isotope half life 8 days If it is safe to feed the hay to cows when 9 the radioactive isotope remains how long did the farmers need to wait to use this hay The farmers needed to wait approximately Round to one decimal place as needed www days for it to be safe to feed the hay to the cows