Susie estimated that she can run for hours at a steady speed of 8m/h. She enters a marathon, a distance of 26meters. How long should it take her to complete the race?

The radioactive isotope of lead, pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.3 hours. if 1 gram of this isotope is present initially, how long will it take for 80% of the lead to decay? (round your answer to two decimal places.)