NAME ______DATE ______PERIOD ______

10.3 Word Problem Practice

Geometric Sequences and Series

1.  ACCOUNTING Each year, the value of a car depreciates by 18%. If you bought a $22,000 car in 2009, what will be its value in 2015?

2.  BACTERIA A colony of bacteria grows at a rate of 10% per day. If there were 100,000 bacteria on a surface initially, about how many bacteria would there be after 30 days?

3.  POPULATION From 1990 to 2000, Florida's population grew by about 23.5%. The population in the 2000 census was 15,982,378. If this rate of growth continues, what will be the approximate population in 2030?
Source: U.S. Census Bureau

4.  SALARY An employee agreed to a salary plan where his annual salary increases by 4.5% each year. He earned $50,081.41 for his tenth year of work.

a.  What was his pay for his first year of work?

b.  To the nearest dollar, how much did he earn for his first 10 years of work?

5.  SCIENCE Bismuth-210 has a half-life of 5 days. This means that half of the original amount of the substance decays every five days. Suppose a scientist has 250 milligrams of Bismuth-210.

a.  Complete the table to show the amount of Bismuth-210 every five days.

Half-Life / 0 / 1 / 2 / 3 / 4
Day / 0 / 5 / 10 / 15 / 20
Amount
(mg) / 250

b.  The amounts of Bismuth-210 can be written as a sequence with the half-life number as the domain. Write an explicit and recursive formula for finding the nth term of the geometric sequence.

c.  How much Bismuth-210 will the scientist have after 50 days? Round to the nearest hundredth.

d.  Graph the function that represents the sequence.

Chapter 10 / 18 / Glencoe Precalculus