A colony contains 1500 bacteria. The population increases at a rate of [tex]$115\%$[/tex] each hour. If [tex]$x$[/tex] represents the number of hours elapsed, which function represents the scenario?

A. [tex]f(x) = 1500(1.15)^x[/tex]
B. [tex]f(x) = 1500(115)^x[/tex]
C. [tex]f(x) = 1500(2.15)^x[/tex]
D. [tex]f(x) = 1500(215)^x[/tex]



Answer :

To determine the correct function representing the growth of the bacteria colony, we need to analyze the given information:
- The initial number of bacteria is 1500.
- The population increases at a rate of [tex]\( 115\% \)[/tex] each hour.
- [tex]\( x \)[/tex] represents the number of hours elapsed.

Since the population increases by [tex]\( 115\% \)[/tex] every hour, this means that each hour, the population is [tex]\( 115\% \)[/tex] of its current population in addition to the initial population. Mathematically speaking:

1. Converting the percentage rate to a decimal:
[tex]\[ 115\% = 1.15 \][/tex]

2. The population each hour is multiplied by a factor of [tex]\( 1.15 \)[/tex].

To express this growth, we use an exponential growth function of the form:
[tex]\[ f(x) = P_0 (\text{rate})^x \][/tex]
Where [tex]\( P_0 \)[/tex] is the initial population, the rate is the growth factor per unit time, and [tex]\( x \)[/tex] is the time in hours.

Substituting the given values (initial population [tex]\( P_0 = 1500 \)[/tex] and growth rate [tex]\( 1.15 \)[/tex]) into the function, we get:
[tex]\[ f(x) = 1500(1.15)^x \][/tex]

Now, let's compare this function to the given options:

1. [tex]\( f(x) = 1500(1.15)^x \)[/tex]
2. [tex]\( f(x) = 1500(115)^x \)[/tex]
3. [tex]\( f(x) = 1500(2.15)^x \)[/tex]
4. [tex]\( f(x) = 1500(215)^x \)[/tex]

The correct representation is option 1:
[tex]\[ f(x) = 1500(1.15)^x \][/tex]

Therefore, the function that correctly represents the scenario where the bacteria population increases by [tex]\( 115\% \)[/tex] each hour is:
[tex]\[ \boxed{f(x) = 1500(1.15)^x} \][/tex]