An insect population after `x` months can be modeled by the graph at left. Complete the table below and write the exponential function that describes this scenario.

months, x population, y
0 12
1 18
2 27
3 40.5

1 answer

To model the insect population growth, we can observe the values you've provided and look for a pattern. The population appears to show exponential growth, specifically it seems to be increasing by a consistent multiplication factor.

First, let's fill in the missing population values for each month:

  • For \(x = 0\), \(y = 12\) (initial population)
  • For \(x = 1\), \(y = 18\)
  • For \(x = 2\), \(y = 27\)
  • For \(x = 3\), \(y = 40.5\)

Finding the Multiplication Factor

To determine the growth factor, we can divide each population value by the population from the previous month:

  1. From \(x = 0\) to \(x = 1\): \[ \frac{18}{12} = 1.5 \]

  2. From \(x = 1\) to \(x = 2\): \[ \frac{27}{18} = 1.5 \]

  3. From \(x = 2\) to \(x = 3\): \[ \frac{40.5}{27} = 1.5 \]

The multiplication factor (growth rate) is consistently 1.5.

Writing the Exponential Function

The general form of an exponential growth function is given by: \[ y = y_0 \cdot r^x \] where:

  • \(y\) is the population at time \(x\),
  • \(y_0\) is the initial population,
  • \(r\) is the growth factor,
  • \(x\) is the number of months.

In our case:

  • \(y_0 = 12\)
  • \(r = 1.5\)

Thus, the exponential function that describes this scenario is: \[ y = 12 \cdot (1.5)^x \]

Final Table of Values

Here is the completed table with the population values for months 0 to 3:

| months, \(x\) | population, \(y\) | |----------------|--------------------| | 0 | 12 | | 1 | 18 | | 2 | 27 | | 3 | 40.5 |

Summary

The exponential function that models the insect population is: \[ y = 12 \cdot (1.5)^x \]