Exponential and Logarithmic Applications

The half-life of strontium-90 is 25 years. How much strontium-90 will remain after 100 years if the initial amount is 4.0 g?

• 3.0g
• 0.25mg
• 0.3g
• 0.25g

Most automobiles depreciate as they get older. Suppose an automobile that originally costs $14,000 depreciates by 20% of its value every year. 
What is the value of this automobile after 5 years?

• $264,539.52
• $4.48
• $4,587.52
• $34,836.48

What is the percent (%) of increaase or decrease in the following equation?

f(x) = 250 (0.95)^x

• Decrease by 95%

• Increase by 5%

• Decrease by 5%

• Increase by 95%

Most automobiles depreciate as they get older. Suppose an automobile that originally costs $20,000 depreciates by 28% of its value every year.  What is the half-life of this automobile?

• 2 years
• 3 years
• 1/2 years
• 2.11 years

A sculpture is increasing in value at a rate of 9% per year, and its value in 2000 was $1500. Write an exponential growth function to model this situation.

• f(t)=1500(1.09)^t
• f(t)=1500(0.09)^t
• f(t)=2000(0.09)^t
• f(t)=1500(9)^t

Suppose a culture of bacteria begins with 5000 cells and dies by 30% each year. Write an equation that represents this situation.

• y=5000(0.7)^x
• y=30(5000)^x
• y=5000(1.3)^x
• y=5000x^x

The equation y = a(1 - r)^x is used for:

• 1/2 life

• Interest

• Exponential Growth

• Exponential Decay

The equation y = a(1 + r)^x is used for:

• Exponential Growth

• Exponential Decay

• Half Life

• Interest

• Half Life

• Exponential Growth

• Interest

If something is growing at a rate of 2% per year, r in the growth formula is:

• .2

• 2

• .02

• 200