Exponential Growth & Decay

Robert invests $800 in an account at 1.8% interest. He will make no deposits or withdrawals on this account for 3 years. Which equation could be used to find the balance, A, in the account after 3 years?

• A=800(1-0.18)³

• A=800(1+0.18)³

• A=800(1-0.018)³

• A=800(1+0.018)³

The current population of a town is 10,000. If the population, P, increases by 20% each year, which equation could be used to find the population after t years?

• P=10000(0.8)^t

• P=10000(0.2)^t

• P=10000(1.2)^t

• P=10000(1.8)^t

Krystal was given $3000 when she turned 2 years old. Her parents invested it at a 2% interest rate. No deposits or withdrawals were made. Which expression can be used to determine how much money Krystal had in the account when she turned 15?

• 3000(1+0.02)¹³

• 3000(1-0.02)¹³

• 3000(1+0.02)¹⁵

• 3000(1-0.02)¹⁵

Mr. Smith invested $2,500 in a savings account that earns 3% interest. He made no additional deposits or withdrawals. Which expression can be used to determine the number of dollars in this account at the end of 4 years?

• 2500(1+0.03)⁴

• 2500(1+0.3)⁴

• 2500(1+0.04)3

• 2500(1+0.4)3

Kathy plans to purchase a car that depreciates at a rate of 14% per year. The initial cost of the car is $21,000. Which equation represents the value, v, of the car after 3 years?

• v=21000(0.14)³

• v=21000(0.86)³

• v=21000(1.14)³

• v=21000(0.86)(3)

Cassandra bought an antique dresser for $500. If the value of the dresser increases at a rate of 6% annually, what will the value of the dresser be at the end of 3 years to the nearest dollar?

• $415

• $590

• $596

• $770

Daniel purchased a new printer for $35,000. Each year it depreciates at a rate of 5%. What will be its approximate value at the end of the fourth year?

• $33,250.00

• 30,008.13

• 28,507.72

• 27.082.33

The expression 3(1.5)^t models the number of bacteria in a culture as a function of the number of hours since the culture was created. What does the 3 represent in this expression?

• There were initially 3 bacteria in the culture.

• The number of bacteria is multiplied by 3 each hour.

• The culture was created 3 hours ago.

• There are 3 bacteria in the culture after one day.

The expression 1.01(1.005)^t gives the amount of money, in thousands of dollars, in Carter's savings account t years after he opens it. What does the 1.01 represent in this expression?

• Cater's savings account had $1,010 in it when he opened it.

• The amount of money in Carter's savings account increase by 1% each year.

• Cater opened the savings account 1 year.

• The account was open for 1.01 years.

The expression 1350(1.05)^t models the average wages, in dollars, in the US as a function of the number of years since 1930. What does the 1.05 represent in this expression?

• The average wages in the US were about $1.05 million in 1930.

• The average wages in the US increase by about 5% each year.

• The average wages double every 1.05 years.

• The average wages in the US decrease by about 5% each year.