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Certain radioactive material decays in such a way that the mass remaining after [tex]t[/tex] years is given by the function

[tex]m(t) = 330e^{-0.03t}[/tex]

where [tex]m(t)[/tex] is measured in grams.

(a) Find the mass at time [tex]t = 0[/tex].
Your answer is:

(b) How much of the mass remains after 20 years?
Your answer is:

Round answers to 1 decimal place.


Sagot :

Certainly! Let's solve this step-by-step:

The given function representing the mass remaining after [tex]\( t \)[/tex] years is:
[tex]\[ m(t) = 330e^{-0.03t} \][/tex]
where [tex]\( m(t) \)[/tex] is in grams.

### Part (a): Find the mass at time [tex]\( t = 0 \)[/tex]

To find the mass at time [tex]\( t = 0 \)[/tex], substitute [tex]\( t = 0 \)[/tex] into the given function:

[tex]\[ m(0) = 330e^{-0.03 \cdot 0} \][/tex]

Since any number raised to the power of 0 is 1:

[tex]\[ m(0) = 330e^0 \][/tex]
[tex]\[ m(0) = 330 \times 1 \][/tex]
[tex]\[ m(0) = 330 \][/tex]

So, the mass at time [tex]\( t = 0 \)[/tex] is:
[tex]\[ \boxed{330.0 \text{ grams}} \][/tex]

### Part (b): How much of the mass remains after 20 years?

To determine the mass remaining after 20 years, substitute [tex]\( t = 20 \)[/tex] into the function:

[tex]\[ m(20) = 330e^{-0.03 \cdot 20} \][/tex]

Let's simplify the exponent first:

[tex]\[ -0.03 \cdot 20 = -0.6 \][/tex]

Now, substitute back into the equation:

[tex]\[ m(20) = 330e^{-0.6} \][/tex]

By evaluating [tex]\( e^{-0.6} \)[/tex] and then multiplying by 330, we find:

[tex]\[ m(20) \approx 181.1 \][/tex]

So, the mass after 20 years is:
[tex]\[ \boxed{181.1 \text{ grams}} \][/tex]

### Summary:
- (a) The mass at time [tex]\( t = 0 \)[/tex] is [tex]\( 330.0 \)[/tex] grams.
- (b) The mass remaining after 20 years is [tex]\( 181.1 \)[/tex] grams.

Both answers have been rounded to 1 decimal place as required.