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  1. A bacteria colony initially has mass tex2html_wrap_inline324 g. After two hours, the colony has mass tex2html_wrap_inline326 g. Find the mass after 5 hours. Find the time it takes for the original mass of the colony to triple.
  2. A metal plate that has been heated cools from tex2html_wrap_inline328 to tex2html_wrap_inline330 in 20 minutes when surrounded by air at a temperature of tex2html_wrap_inline332 . What will the temperature of the plate be be after one hour of cooling? When will the temperature of the plate reach tex2html_wrap_inline334 ?
  3. Just before midday the body of an apparent homicide victim is found in a room that is kept at a constant temperature of tex2html_wrap_inline336 . At 12 noon the temperature of the body is tex2html_wrap_inline338 and at 1 P.M. it is tex2html_wrap_inline340 . Assume that the temperature of the body at the time of death was tex2html_wrap_inline342 . What is the time of death?
    1. Radioactive radium has a half-life of approximately 1600 years. What percentage of a present amount remains after 100 years?
    2. If radioactive material decays continuously at a rate proportional to the amount present, find the half-life of the material if after one year, 99.57 % of an initial amount still remains.

Roxanne Tisch
Tue Sep 24 13:59:38 EDT 1996