The mass of a substance, which follows a continuous exponential growth model, is being studied in a lab. A sample increases continuously at a relative rate of 9% per day. Find the mass of the sample after five days if there were 354 grams of the substance present at the beginning of the study.

Do not round any intermediate computations, and round your answer to the nearest tenth.



Answer :

To solve the problem of determining the mass of a substance after five days of continuous exponential growth, we follow these steps:

1. Identify the given variables:
- Initial mass ([tex]\(M_0\)[/tex]) = 354 grams
- Growth rate per day ([tex]\(r\)[/tex]) = 9% per day = 0.09 (in decimal form)
- Time period ([tex]\(t\)[/tex]) = 5 days

2. Understand the exponential growth formula:
The formula for continuous exponential growth is given by:
[tex]\[ M(t) = M_0 \cdot e^{rt} \][/tex]
where:
- [tex]\(M(t)\)[/tex] is the mass after time [tex]\(t\)[/tex],
- [tex]\(M_0\)[/tex] is the initial mass,
- [tex]\(e\)[/tex] is the base of the natural logarithm (approximately equal to 2.71828),
- [tex]\(r\)[/tex] is the growth rate,
- [tex]\(t\)[/tex] is the time period.

3. Substitute the given values into the formula:
[tex]\[ M(5) = 354 \cdot e^{0.09 \cdot 5} \][/tex]

4. Calculate the exponent:
[tex]\[ 0.09 \cdot 5 = 0.45 \][/tex]

5. Evaluate the exponential function:
[tex]\[ e^{0.45} \approx 1.568312185490169 \][/tex]
Note: This is the approximation of the value of [tex]\(e^{0.45}\)[/tex].

6. Calculate the final mass:
[tex]\[ M(5) = 354 \cdot 1.568312185490169 \approx 555.1825136635197 \text{ grams} \][/tex]

7. Round the final answer to the nearest tenth:
Thus, the mass after five days, rounded to the nearest tenth, is:
[tex]\[ \boxed{555.2 \text{ grams}} \][/tex]

Therefore, the mass of the sample after five days is approximately 555.2 grams.