Exponential Functions Word Problems Doubles or Triples

Which equation describes the story below?

You start with $5 and triple your money every day.

• y=5(3)^x

• y=5^x

• y=5(3x)

• y=15^x

A particular type of cell triples in number every hour. Which function can be used to find the number of cells present at the end of h hours if there are initially 6 of these cells?

• f(h) = 3(6)^h

• f(h) = 6x^h

• f(h) = 6(3)^h

• f(h) = 3(6h)

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. What will the cost be after 4 years?

• C(t) = 12000(1.06)^t ; $3149.72

• C(t) = 12000(.06)^t ; $3149.72

• C(t) = 12000(.06)^t ; $1472.95

• C(t) = 12000(1.06)^t ; $15149.72

The bacteria on an old pizza starts out with 5 bacteria and doubles every 4 days.

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.

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Match the word problem describing Jenny's investment, which is expected to triple each year, to the correct equation.

• y = 20,000(3^x)

• y = 20,000(1/3^x)

• y = 20,000(1.33^x)

• y = 20,000(0.67^x)

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

• f(x)=400(1+3)^x

• f(x)=400(1-0.03)^x

• f(x)=400(1+0.03)^x

• f(x)=400(0.03)^x

The number of research papers in Professor Sycamore area of expertise has been increasing by 5% every year. Given that 30,010 research papers were published this year. Assuming the trend continues, which equation projects the amount of research papers published in x years?

• y = 30,010 (.05)^x

• y = 30,010 (1.05)^x

• y = 30,010 (.95)^x

• y = 30,010 (5)^x

Write an equation that models the following situation: Samantha's hair was known to grow very rapidly. It began at a length of 6 in and grew at a rate of 14% a week. (HINT: Write out the equation on a separate piece of paper and then simplify inside the parenthesis)

• y=6(0.14)^x

• y=6(1+14)^x

• y=6(1.14)^x

• y=6(0.86)^x

Write an equation that models the following situation: Samantha's hair was known to grow very rapidly. It began at a length of 6 in and grew at a rate of 14% a week. (HINT: Write out the equation on a separate piece of paper and hen simplify inside the parenthesis)

• y=6(0.14)^x

• y=6(1+14)^x

• y=6(1.14)^x

• y=6(0.86)^x