College

What is the rate of decay, [tex]r[/tex] (expressed as a decimal), for data best modeled by the exponential function [tex]y = 63.4(0.92)^x[/tex]?

A. [tex]r = 36.6[/tex]
B. [tex]r = 0.92[/tex]
C. [tex]r = 0.08[/tex]
D. [tex]r = 63.4[/tex]

Answer :

To find the rate of decay, [tex]\( r \)[/tex], in the exponential function [tex]\( y = 63.4(0.92)^x \)[/tex], you can use the structure of the exponential function [tex]\( y = a(b)^x \)[/tex], where [tex]\( b \)[/tex] is the base representing the growth or decay factor.

In this particular function:

- [tex]\( a = 63.4 \)[/tex] is the initial amount.
- [tex]\( b = 0.92 \)[/tex] is the base.

For exponential decay models, the rate of decay, [tex]\( r \)[/tex], can be determined by:

[tex]\[ r = 1 - b \][/tex]

Here, we substitute the given value of [tex]\( b \)[/tex]:

1. Calculate [tex]\( r \)[/tex]:

[tex]\[ r = 1 - 0.92 \][/tex]

2. Subtract to find [tex]\( r \)[/tex]:

[tex]\[ r = 0.08 \][/tex]

So, the rate of decay [tex]\( r \)[/tex] is [tex]\( 0.08 \)[/tex].

This means that the data decreases by approximately 8% each time period. Hence, the correct answer is:

[tex]\( r = 0.08 \)[/tex].