Exponential Functions from Word Problems

The amount of cola in a soda machine decreases by a rate of 5% each hour. The amount of cola in the machine was originally 75 gallons. Which function models the amount of cola in gallons after h hours?

• f(h) = 75(-5)^h

• f(h) = -5(75)^h

• f(h) = .95(75)^h

• f(h) = 75(.95)^h

Write an exponential function to model the situation. Then solve. The cost of tuition at a college is $12,000 and is increasing at a rate of 6% per year. Which equations represents this situation?

• C(t) = 1.06(12000)^t

• C(t) = 12000(.06)^t

• C(t) = 12000(.06)^t

• C(t) = 12000(1.06)^t

Write an exponential function to model the situation. You invest $1500. Your investment increases at a rate of 3.5%.

• B(t) = 1500(0.965)^t

• B(t) = 1500(1.035)^t

• B(t) = 1500(.035)^t

• B(t) = 1500(1.965)^t

Write an exponential function to model the situation. The value of a car is $18000 and is depreciating at a rate of 12% per year.

• V(t) = .88(18000)^t

• V(t) = .12(18000)^t

• V(t) = 18000(.88)^t

• V(t) = 18000(.12)^t

In Jack and the beanstalk, the beanstalk grows very rapidly. It began at a length of 3 ft and grew at a rate of 14% per minute

Write the exponential function for this example

• y=6(0.14)^x

• y=3(17)^x

• y=3(1.14)^x

• y=3(0.86)^x

• y=6(1.04)^x

Eduardo currently has 500 followers on TikTok. He makes a video after the basketball game and it goes viral! Since he became internet famous, the number of followers is increasing by 25% daily. Write an exponential function that represents the relationship between x, the number of days since Eduardo posted the video and y, the total number of followers Eduardo has.

Mathematical Equivalence

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A new savings account is opened with $400 and gains 3% every year. What is the exponential function?

y = ​ (a)   ( 1 ​ (b)   ​ (c)   )^x (^ means to power of x - x is the exponent)

• 400

• +

• 0.03

• 3

• 0.3

• 0.97

• 4

If the population of a city is 50,000 and grows at a continuous rate of 3% per year, what will be the population after 5 years?

• 58,091

• 55,000

• 60,000

• 50,000

In Jack and the beanstalk, the beanstalk grows very rapidly. It began at a length of 3 ft and grew at a rate of 14% per minute Write the exponential function for this example

• y=6(0.14)^x

• y=3(17)^x

• y=3(1.14)^x

• y=3(0.86)^x

• y=6(1.04)^x

The equation Q = 12e^{-.09t is given to show the amount of an element remaining after t years. how long will it take for the element to reach 3 mg?}

• 4.5 years

• 12.7 years

• 2.7 years

• 15.4 years