High School

You win a prize and are offered two choices:

Choice A: [tex]$0.10[/tex] on January 1, [tex]$0.20[/tex] on January 2, [tex]$0.40[/tex] on January 3, [tex]$0.80[/tex] on January 4, doubling the amount each day.

Choice B: [tex]$5.00[/tex] on the first day, [tex]$10.00[/tex] on the second day, [tex]$15.00[/tex] on the third day, getting [tex]$5.00[/tex] more each day.

Which choice can be defined using an exponential function? What is the function?

A. Choice A, [tex]A_t = 0.10(2)^{t-1}[/tex]

B. Choice A, [tex]A_t = (0.10)^{t-1}[/tex]

C. Choice B, [tex]A_t = 5.00 + 5.00t[/tex]

D. Choice B, [tex]A_t = 5.00 + 5.00(t-1)[/tex]

Answer :

To determine which choice can be defined using an exponential function, let's look at each option separately:

Choice A:
- On January 1, you receive [tex]$0.10.
- Each subsequent day, the amount doubles: $[/tex]0.20 on January 2, [tex]$0.40 on January 3, $[/tex]0.80 on January 4, and so forth.

This pattern follows exponential growth because the amount is multiplied by a constant factor (2) each day. An exponential function can be used to represent this type of growth. The function for the amount received on day [tex]\( t \)[/tex] can be written as:
[tex]\[ A_t = 0.10 \times (2)^{t-1} \][/tex]

Choice B:
- On January 1, you receive [tex]$5.00.
- Each subsequent day, the amount increases by $[/tex]5.00: [tex]$10.00 on January 2, $[/tex]15.00 on January 3, and so on.

This pattern follows an arithmetic progression because a fixed amount ($5.00) is added each day. An arithmetic sequence can be represented by a linear function. The function for the amount received on day [tex]\( t \)[/tex] can be written as:
[tex]\[ A_t = 5.00 + 5.00(t-1) \][/tex]

Conclusion:
Choice A involves doubling the amount each day, which is characteristic of exponential growth. Therefore, the function for Choice A, [tex]\( A_t = 0.10(2)^{t-1} \)[/tex], represents an exponential function.

This is the choice that can be defined using an exponential function.