A factory produces 1,250,000 toys each year. The number of toys is expected to increase by about 150% per year. Which model can be used to find the number of toys, [tex]\( n \)[/tex] (in millions), being produced in [tex]\( t \)[/tex] years?

A. [tex]\( n = \frac{2.5(1.5)}{t}, t = 0 \)[/tex]
B. [tex]\( n = 15 t^2 + 1.25 \)[/tex]
C. [tex]\( n = 1.5 t + 1.25 \)[/tex]
D. [tex]\( n = 1.25 \cdot 2.5^t \)[/tex]



Answer :

Sure! Let's walk through the process of deciding which model accurately represents the number of toys produced by the factory given an initial production and a yearly increase rate:

1. Initial Production:
- The factory produces 1,250,000 toys each year. This can be written as 1.25 million toys (since 1,000,000 is one million).

2. Yearly Increase Rate:
- The production of toys increases by 150% each year.

3. Understanding the Increase:
- A 150% increase implies that next year's production will be 2.5 times this year's production (because the original amount plus 150% of it results in 100% + 150% = 250% or 2.5 times the initial amount).

4. Choosing the Model:
- We need to model this as an exponential growth problem, where the new number of toys produced each year is a multiple (in this case, 2.5 times) of the previous year's production.
- The general formula for exponential growth is:
[tex]\[ n = \text{initial}_\text{value} \times (\text{growth}_\text{factor})^t \][/tex]
- This translates to:
[tex]\[ n = 1.25 \times (2.5)^t \][/tex]
where [tex]\( n \)[/tex] is the number of toys produced in millions, and [tex]\( t \)[/tex] is the number of years since the initial production.

5. Evaluating Given Options:
- The given models for [tex]\( n \)[/tex] are:
1. [tex]\( n = \frac{2.5(1.5)}{t}, \; t = 0 \)[/tex]
2. [tex]\( n = 15 t^2 + 1.25 \)[/tex]
3. [tex]\( n = 1.5 t + 1.25 \)[/tex]
4. [tex]\( n = 1.25 \cdot 2.5^t \)[/tex]

6. Matching Our Model:
- Looking at our derived model:
[tex]\[ n = 1.25 \cdot 2.5^t \][/tex]
- This matches option 4 exactly.

Therefore, the correct model to find the number of toys [tex]\( n \)[/tex] (in millions) being produced in [tex]\( t \)[/tex] years is:
[tex]\[ n = 1.25 \cdot 2.5^t \][/tex]