1. December 5 th copyright2009merrydavidson Practice Rounding: a)To the tenths b)To the hundredths 1)1.9652) -1.484 3)2.7394) 9.999

2. Half life problems…. The definition of half-life is the time it takes for something to reduce to half as much. 1) The half-life of a material is 100 years. If you have 1000 grams, how much will remain after 500 years. A = Pe -kt Part 1)find kPart 2) answer what is asked.5 = 1e -k(100) Store “k” A = 1000e - k (500) 31.25 grams

3. Half life problems…. 2) Let “Q” represent the mass of radium whose half-life is 1620 years. The quantity of radium present after “t” years is given by a)Determine the initial quantity (when t = 0). b)Determine the quantity Remaining after 1000 years. 16 grams 10.43 grams

4. 3)One hundred grams of radium are stored in a container. The amount R (in grams) of radium present after “t” years can be modeled by. After how many years will only 5 grams of radium be present? about 6967 years

5. Population 4)The population P of a city is given by P = 95,300e 0.055t where t = 0 represents 1996. According to this model, when did the population reach 150,000? 2004

6. 5) Appreciation/Depreciation A = P(1 + r) t A = amount after t years P = the initial amount 1 + r = growth or decay factor t = the number of years Harley Davidson motorcycles depreciate in value. If Mrs. Davidson’s 2002 road king cost $34,000 and the rate of depreciation is 5% yearly, what will it be worth exactly 5 years later? A = 34,000(1 -.05) 5 $26,308.55