Quiz about Percent Growth and Decay

Question 1

Determine if the following is an example of a linear OR exponential situation:

A certificate of deposit earns 4% interest each year.

Accepted Answer

Exponential

Answer

Linear

Answer

Neither

Question 2

Kelli's mom takes a 400 mg dose of aspirin. Each hour, the amount of aspirin in a person's system decreases by about 29%. Write an equation to represent the amount of aspirin left in her system x hours after she took the aspirin.

Accepted Answer

$$y=400\left(0.71\right)^x$$

Answer

$$y=400\left(1.29\right)^x$$

Answer

$$y=400-29x$$

Answer

$$y=400\left(0.29\right)^x$$

Question 3

For the function $$t\left(x\right)=10,000\left(1.02\right)^x$$ , determine if it represents exponential growth or decay AND determine the percent increase/decrease.

Accepted Answer

growth:

2% increase

Answer

growth:

0.2% increase

Answer

decay:

98% decrease

Answer

decay:

2% decrease

Question 4

The value of an early American coin increases in value at a rate of 6.5% annually. If the purchase price of the coin this year is $1,950, write an equation to model the value in x years.

Accepted Answer

$$y=1950\left(1.065\right)^x$$

Answer

$$y=1950\left(0.935\right)^x$$

Answer

$$y=1950+6.5x$$

Answer

$$y=1950+1.65x$$

Question 5

For the function $$f\left(n\right)=50\left(0.1\right)^n$$ , determine if it represents exponential growth or decay AND determine the percent increase/decrease.

Accepted Answer

decay:

90% decrease

Answer

growth:

10% increase

Answer

growth:

90% increase

Answer

decay:

10% decrease

Question 6

You need $200 to start a snow cone stand for the summer. You borrow the money from a bank that charges 4% interest compounded monthly. Choose the expression that represents the amount owed after 3 years.

Accepted Answer

$$200\left(\left(1+\frac{0.04}{12}\right)^{12}\right)^3$$

Answer

$$200\left(\left(1.04\right)^{12}\right)^3$$

Answer

$$200\left(\left(1+\frac{0.04}{3}\right)^3\right)^{12}$$

Question 7

The value of a house increases in value by 1.5% each year.

Accepted Answer

Exponential

Answer

Linear

Answer

Neither

Question 8

Malik bought a new car for $15,000. He was told that the car's value will decrease by 15% every year. Write an equation to represent the car's value after x years.

Accepted Answer

$$y=15,000\left(0.85\right)^x$$

Answer

$$y=15000-15x$$

Answer

$$y=15,000\left(0.15\right)^x$$

Answer

$$y=15,000-85x$$

Question 9

The original value of a painting is $1400, and the value increases by 9% each year. Write an exponential growth function to model this situation.

Accepted Answer

y=1400(1.09)^x

Answer

y=1.09(1400)^x

Answer

y=1400(.91)^x

Answer

y=1.09x

Question 10

Which of the following functions shows an initial amount of $15 and an increase of 35% each year?

Accepted Answer

y = 15(1 + 0.35)^x

Answer

y = 15(35)^x

Answer

y = 15(0.35)^x

Answer

y = 35(1+ 0.15)^x

Question 11

Is the pictured graph growth, decay, or linear or none?

Accepted Answer

Exponential Growth

Answer

Exponential Decay

Answer

Linear

Answer

None

Question 12

Is this exponential growth or decay?

Accepted Answer

Decay

Answer

Growth

Question 13

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

Accepted Answer

y=5000(1 - 0.30)^x

Answer

y=30(5000)^x

Answer

y=5000(1 + 0.30)^x

Answer

y=5000xx

Question 14

Twenty years ago, Mr. Davis purchased his home for $160,000. Since then, the value of the home has increased about 5% per year. How much is the home worth today?

Accepted Answer

$424,527.63

Answer

$176,783.29

Answer

$57,357.75

Answer

$532,041,076.80

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