Growth and Decay

Is this exponential growth or decay?

• Growth, because of 7
• Decay, because of 1.2
• Growth because of 1.2
• Decay because of 7

P = 8(1.23)^t

What is the growth rate?

Write as a percent!

P = 8(1.23)^t

What is the initial quantity?

P = 8(1.23)^t

Is the function growth or decay?

Check the box:

• Growth

• Decay

Q = 3.1(0.78)^t

What is the DECAY rate?

Write as a percent!

CAREFUL!!!

The value of a car is $15,000 and depreciates at a rate of 8% per year. What is the exponential equation?

• y=8(15,000)^x
• y=15,000(1.08)^x
• y=15,000(0.92)^x
• y=15,000(0.08)^x

An air freshener starts with 30 grams of fluid, and the amount of fluid decreases by 12% per day. Express the amount of grams of freshener, Q, that remains, t, days after it has begun being used.

Check the BEST answer: (HINT: that means simplify what is in the parenthesis)

• Q=30(1+0.12)^t

• Q=30(1-0.12)^t

• Q=30(0.88)^t

• Q=12(1.30)^t

Pick the equation that is exponential decay

• y=2000(0.88)
• y=0.5(1.88)
• y=-4x
• y= -7+10x

The population of Winnemucca, Nevada, can be modeled by P=6191(1.04)^t where t is the number of years since 1990. What percent did the population increase each year?

• 4%
• It doesn't say
• I don't know
• 400%

A 78 gram sample of Uranium loses half of its mass each year.  What is the exponential equation? 

• y=78(0.5)^x
• y=78(1.5)^x
• y=78(2)^x