Writing Exponential Functions for Word Problems

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

• y = 15(35)^x
• y = 15(1.35)^x
• y = 15(0.35)^x
• y = 35(1.15)^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.

• y=6(0.14)^x
• y=6(1+14)^x
• y=6(1.14)^x
• y=6(0.86)^x

There were 417 cell phones sold at an electronics store in January. Since then, cell phone sales at this store have increased at a rate of 3.75% per month. At this rate of growth, which function can be used to determine the monthly cell phone sales x months after January?

• f(x) = 417(3.75)^x
• f(x) = 417(0.0375)^x
• f(x) = 417(1.0375)^x
• f(x) = 417(1.375)^x

The population of Pallet Town increases by 15% every year. If there are currently 190,000 people living there, what will be the population in 13 years?

If necessary, round your answer to the nearest whole number.

• 4 people.

• 22,972 people.

• 1,169,030 people.

• 1,188,311 people.

A particular type of cell doubles in number every hour.  which function can be used to predict the number of cells present at the end of h hours if there are initially 4.

• a
• b
• c
• d

If you have $10, and your money doubles every year, how much money will you have in 10 years?

• $50

• $100

• $5120

• $10240

• 9600

• 12,800

• 200

• 8000

• 14,000 employees

• 12,386 employees

• 40,360 employees

• 15,748 employees

Identify the common ratio (multiplier) of the function f(x)=2(4)^x.

• 2
• 4
• (2)^x
• 8

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