A real, inverted, and larger image is seen in a converging lens. The object must be located: a) between 2FI and FI
b) further than 2F1
c) to FI
d) between Fi and the lens

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.)