Exponential Growth and Decay Word Problems with Half-Life and Doubling Life

If 10 mg of iodine 131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.

• 25mg

• 25g

• 10g

• 10mg

Write and exponential function for the following problem: Mrs. Madison starts the year off with 100 pencils. Each week, half of the pencils disappear. How many would be left after x weeks?

Write an equation for this problem: A population of 1200 bacteria is doubling each day for x days.

You drink a beverage with 120 mg of caffeine. Each hour, the caffeine in your system decreases by about 12%. How long until you have 10mg of caffeine?

• 19 to 20 hours

• 10 to 20 hours

• 15 to 16 hours

• 5 to 6 hours

Is this exponential growth or decay?

• Growth, because of 7

• Growth because of 1.2

• Decay, because of 1.2

• Decay because of 7

What type of function does the equation y = 2^xrepresent?

• Exponential Decay

• Linear

• Exponential Decay

• Exponential Growth

Is this exponential growth or decay?

• Growth

• Decay

A sailboat that costs $5,950 decreases in value by a decay factor of .89 per year. How much will the boat be worth after 6 years?

• $0.01

• $5,178.97

• $2,992.96

• $2,957.04

Due to its weakening steel industry, Canalave Town has been experiencing a population decline of 10% every year. The current population is 74,000 people. Assuming the trend continues, which equation projects the population in x years?

• y = 74,000 (0.10)^x

• y = 74,000 (0.90)^x

• y = 74,000 (1.10)^x

• y = 74,000 (1.90)^x

A city doubles its size every 64 years. If the population is currently 225,000, what will the population be in 128 years?

• The population will be 225,000.

• The population will be 450,000.

• The population will be 900,000.

• The population will be 1,800,000.